The 35th International Symposium on Lattice Field Theory

18-24 June 2017
Palacio de Congresos
Europe/Madrid timezone
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Contribution List

Displaying 420 contributions out of 420
Type: Parallel Session: Weak Decays and Matrix Elements
Track: Weak Decays and Matrix Elements
We report on the status of our calculation of the exclusive semileptonic decay, $B \rightarrow \pi\ell\nu$; a key process in the determination of the CKM matrix element $V_{ub}$. The M\"{o}bius domain wall action is used for both light and heavy quarks on gauge ensembles that include the effects of $2+1$ flavours of quarks in the sea at three values of the lattice spacing: $a\approx0.08~\mathrm{fm ... More Presented by Dr. Brian COLQUHOUN on 19 Jun 2017 at 14:50 Type: Parallel Session: Weak Decays and Matrix Elements Track: Weak Decays and Matrix Elements Using the MILC 2+1 flavor asqtad quark action ensembles, we are calculating the form factors$f_0$and$f_+$for the semileptonic$B_s \rightarrow K \ell\nu$decay. A total of six ensembles with lattice spacing from$\approx0.12$to 0.06 fm are being used. At the coarsest and finest lattice spacings, the light quark mass$m_l$is one-tenth the strange quark mass$m_s$. At the intermediate latti ... More Presented by Prof. Steven GOTTLIEB on 19 Jun 2017 at 15:10 Type: Parallel Session: Weak Decays and Matrix Elements Track: Weak Decays and Matrix Elements The quark flavor sector of the Standard Model is a fertile ground to test any new physics effect through the Unitarity test of the Cabbibo-Kobayashi-Maskawa (CKM) matrix. We present a lattice QCD calculation of the scalar and the vector form factors (over a large$q^2$region including$q^2=0$) associated with the$D\rightarrow Kl\nu$semi-leptonic decay. The central CKM matrix element,$V_{cs}$i ... More Presented by Dr. Bipasha CHAKRABORTY on 20 Jun 2017 at 18:30 Type: Parallel Session: Weak Decays and Matrix Elements Track: Weak Decays and Matrix Elements We present our calculation of$D \to \pi$and$D \to K$semileptonic form factors in 2+1 flavor lattice QCD. We simulate three lattice cutoffs$a^{-1} \sim $2.5, 3.6 and 4.5 GeV with pion masses as low as 230 MeV. The Moebius domain-wall action is employed for both light and charm quarks. We present our results for the vector and scalar form factors and discuss their dependence on the latt ... More Presented by Takashi KANEKO on 20 Jun 2017 at 17:10 Type: Parallel Session: Weak Decays and Matrix Elements Track: Weak Decays and Matrix Elements The decay$\Lambda_b \to \Lambda(1520)(\to p^+ K^-) \mu^+\mu^-$is a baryonic analogue of the mesonic process$\bar{B}^0 \to \bar{K}^{*0}(892)(\to \pi^+ K^-) \mu^+\mu^-$, in which tensions between theory and experiment have been observed. Here we give an update on our lattice calculations of$\Lambda_b \to \Lambda(1520)$form factors. To allow an exact projection to the$J^P=\frac32^-$quantum nu ... More Presented by Mr. Gumaro RENDON on 20 Jun 2017 at 15:20 Type: Parallel Session: Weak Decays and Matrix Elements Track: Weak Decays and Matrix Elements We present first results from our analysis of the form factors for$\bar{B}\rightarrow D^\star \ell \bar{\nu}$decay at non-zero recoil. Our analysis includes 15 MILC asqtad ensembles with$N_f=2+1$flavors of sea quarks and lattice spacings ranging from$a\approx0.15$~fm down to$0.045$~fm. The valence light quarks employ the asqtad action, whereas The$b$and$c$quarks are treated using the Fe ... More Presented by Dr. Alejandro VAQUERO AVILÉS-CASCO on 19 Jun 2017 at 17:00 Type: Parallel Session: Hadron Spectroscopy and Interactions Track: Hadron Spectroscopy and Interactions We present preliminary results for the masses and decay constants of the$\eta$and$\eta^\prime$mesons using CLS$N_f = 2+1$ensembles. One of the major challenges in these calculations are the large statistical fluctuations due to disconnected quark loops. We tackle these by employing a combination of noise reduction techniques which are tuned to achieve the optimal noise reduction per cost. ... More Presented by Jakob SIMETH on 20 Jun 2017 at 18:10 Type: Parallel Session: Hadron Structure Track: Hadron Structure We present an update on our lattice QCD calculation of the radiative process$\pi \pi \to \pi \gamma^{*}$, which is enhanced by the presence of the$\rho$resonance. The calculations were performed with 2+1 clover fermions at$m_\pi \approx 320$MeV and$L$approx$3.6$fm, and we have now analyzed the data from the full set of gauge configurations. Using the results of our recent high-precision c ... More Presented by Dr. Luka LESKOVEC on 23 Jun 2017 at 18:30 Type: Parallel Session: Hadron Spectroscopy and Interactions Track: Hadron Spectroscopy and Interactions We present a comparative analysis of various methods to study the$\rho \rightarrow \pi \pi$resonance. We use$N_f=2+1$of clover fermions at a pion mass of approximately$320$MeV and a lattice size of approximately$3.6$fm, to investigate two ways of determining the parameters of the elastic$\pi\pi$scattering; one is by extracting infinite volume phase shifts using the L\"uscher analysis an ... More Presented by Mr. Srijit PAUL on 19 Jun 2017 at 17:00 Type: Poster Session: Poster Session We summarize previous work on$\bar b \bar b u d$four-quark systems in the Born-Oppenheimer approximation and discuss first steps towards an extension to the theoretically more challenging$b \bar b u \bar d$system. Strategies to identify a possibly existing$b \bar b u \bar d$bound state are discussed und first numerical results are presented. Presented by Ms. Antje PETERS on 20 Jun 2017 at 20:30 Type: Parallel Session: Theoretical Developments Track: Theoretical Developments The gradient flow and its small flow-time expansion provide a very versatile method to represent renormalized composite operators in a regularization-independent manner. This technique has been utilized to construct typical Noether currents such as the energy-momentum tensor and the axial-vector current in lattice gauge theory. In this paper, we apply the same technique to the supercurrent in the ... More Presented by Ms. Aya KASAI on 21 Jun 2017 at 10:00 Type: Parallel Session: Algorithms and Machines Track: Algorithms and Machines We propose a new updating scheme to perform constrained hybrid Monte Carlo on lattices with different scales. Starting from a coarse lattice, the scheme preserves the long distance physics and the evolution fills in the short distance physics on the fine lattice. Methods of tuning lattice parameters to follow the renormalization group transformation are explored. With this scheme we expect to redu ... More Presented by Jiqun TU on 20 Jun 2017 at 15:40 Type: Parallel Session: Software Development Track: Software Development Multigrid preconditioning has proved to deal efficiently with the critical slowing down of standard Krylov solvers. In the literature two slightly different approaches have been developed, referred to as MG-CGR and DD-αAMG. Several libraries implementing multigrid solvers are publicly available for both CPU and GPU codes. In this talk we will consider the QUDA and DDalphaAMG library which implem ... More Presented by Mr. Simone BACCHIO on 23 Jun 2017 at 15:20 Type: Parallel Session: Hadron Spectroscopy and Interactions Track: Hadron Spectroscopy and Interactions We give a status report for our large scale simulation of 2+1 flavor lattice QCD at the physical point. The configurations are generated with the stout-smeared O(a)-improved Wilson quark action and the Iwasaki gauge action. We present some preliminary physics results and discuss the benefit and the significance of a large spatial volume. Presented by Prof. Yoshinobu KURAMASHI on 22 Jun 2017 at 15:00 Type: Parallel Session: Hadron Structure Track: Hadron Structure The results of a calculation of the hadronic vacuum polarization contribution to the muon anomalous magnetic moment are presented. We discuss different methods for controlling the infrared regime of the vacuum polarization function. This includes Padé fits, time moments and the time-momentum representation. We correct our results for finite-volume effects by combining the Gounaris-Sakurai ... More Presented by Prof. Hartmut WITTIG on 22 Jun 2017 at 15:00 Type: Parallel Session: Physics Beyond the Standard Model Track: Physics Beyond the Standard Model We present a new method to calculate the continuum beta function in gauge theories, using the gradient flow and p-regime simulations. The infinite volume renormalization scheme has the flow time as its only scale and determines the beta function in the strong coupling regime relevant for the spectrum with spontaneously broken chiral symmetry. This bridges the gap between other methods using simula ... More Presented by Prof. Kieran HOLLAND on 20 Jun 2017 at 16:00 Type: Plenary Session: Plenary Session - X I will report the current status of RBC/UKQCD's calculation of the hadronic vacuum polarization contribution to the muon anomalous magnetic moment. I will review quark connected and disconnected contributions as well as progress on QED and strong isospin-breaking contributions at the physical pion mass. I will furthermore present a combined lattice and R-ratio analysis. Presented by Christoph LEHNER on 24 Jun 2017 at 11:30 Type: Parallel Session: Algorithms and Machines Track: Algorithms and Machines I will present a method for calculating eigenvectors of the staggered Dirac operator based on the Golub-Kahan-Lanczos bidiagonalization algorithm. Instead of using orthogonalization during the bidiagonalization procedure to increase stability, we choose to stabilize the method by combining it with an outer iteration that refines the approximate eigenvectors obtained from the inner bidiagona ... More Presented by James OSBORN on 19 Jun 2017 at 15:50 Type: Parallel Session: Theoretical Developments Track: Theoretical Developments The Abelian Color Cycle (ACC) technique is a method to dualize non-abelian lattice field theories. The crucial step of this approach is to decompose the action into a sum over complex numbers by writing explicitly all the traces, matrix and vector multiplications. This allows for the factorization of the Boltzmann weight into local factors, that are then Taylor expanded. After the analytical inte ... More Presented by Ms. Carlotta MARCHIS on 21 Jun 2017 at 11:50 Type: Parallel Session: Hadron Spectroscopy and Interactions Track: Hadron Spectroscopy and Interactions A stochastic source using a dilute grid of source points and incorporating momentum-based smearing is used to generate the correlation function of the proton at rest and in a boosted frame. The dependence of the error terms on the number of source points and source separation is studied. Calculations on a$24^3\times 48$lattice demonstrate that this novel technique yields reduced statistical erro ... More Presented by Dr. Jiajun WU on 20 Jun 2017 at 17:10 Type: Parallel Session: Nonzero Temperature and Density Track: Nonzero Temperature and Density We present a study of the finite density lattice Thirring model in 2 dimensions using the world-line/fermion-bag algorithm. The model has features similar to QCD and provides a test case to explore the accuracy of various methods to solve sign problems. In the massless limit and with open boundary conditions we show that the sign problem is an artifact of the auxiliary field approach and is comple ... More Presented by Dr. Jarno RANTAHARJU on 22 Jun 2017 at 17:30 Type: Parallel Session: Algorithms and Machines Track: Algorithms and Machines Owing to its success in removing the critical slowing down of Dirac linear systems, adaptive multigrid is now a standard solver in the arsenal of tools that the lattice field theorist expects. In this work we report on the latest progress in improving the strong scaling of adaptive multigrid algorithms when running on GPU-accelerated architectures using the QUDA library. Techniques include Schwa ... More Presented by Dr. Kate CLARK on 19 Jun 2017 at 14:50 Type: Poster Session: Poster Session Several important observables, like the quark condensate and the Taylor coefficients of the QCD pressure with respect to the chemical potential, are based on the trace of the inverse Dirac operator or its powers. Such traces are traditionally estimated with "noise vectors". We explore alternative approaches based on polynomial approximations of the inverse Dirac operator. Presented by Mr. Philippe DE FORCRAND on 20 Jun 2017 at 20:30 Type: Parallel Session: Theoretical Developments Track: Theoretical Developments This is the second talk followed to the first one of general formulation proposing a new type of lattice field theory without lattice chiral fermion problem. It has been formulated by the momentum space by introducing a new continuum momentum on the lattice and has non-local nature in the coordinate space. The recovery of associativity of the non-local product led us to this new formulat ... More Presented by Prof. Noboru KAWAMOTO on 21 Jun 2017 at 10:40 Type: Parallel Session: Theoretical Developments Track: Theoretical Developments We propose an unconventional formulation of lattice field theories which is quite general, although originally motivated by the quest of exact lattice supersymmetry. Two long standing problems have a solution in this context: 1) Each degree of freedom on the lattice corresponds to 2^d degrees of freedom in the continuum, but all these doublers have(in the case of fermions) the same chirality and ... More Presented by Mr. Alessandro D'ADDA, Prof. Noboru KAWAMOTO on 21 Jun 2017 at 10:20 Type: Poster Session: Poster Session We describe our experiences porting the Regensburg implementation of the DD-$\alpha$AMG solver from the first-generation Intel Xeon Phi processor (Knights Corner) to its successor (Knights Landing). We present the performance of the code on a single processor as well as the scaling behavior on many nodes of QPACE 3, which utilizes Intel's new Omni-Path fabric. Presented by Mr. Daniel RICHTMANN on 20 Jun 2017 at 20:30 Type: Parallel Session: Nonzero Temperature and Density Track: Nonzero Temperature and Density We estimate the production rate of photons from the quark-gluon plasma in lattice QCD. The production of weakly-interacting particles from a strongly-interacting medium has applications to particle cosmology and heavy-ion phenomenology. We propose a new observable which gives us better control over the systematic uncertainty in estimating the rate at large photon momenta. The relevant Euclidean ... More Presented by Dr. Tim HARRIS on 23 Jun 2017 at 15:40 Type: Parallel Session: Nonzero Temperature and Density Track: Nonzero Temperature and Density In order to estimate the photon rate from the Euclidean vector current correlation functions, an inverse problem for the vector-channel spectral function must be solved. We use both a direct model for the spectral function and a model-independent estimate from the Backus-Gilbert method to give a robust estimate for the photon rate at momenta close to its maximum. At low photon momenta, the exis ... More Presented by Mr. Aman STEINBERG on 23 Jun 2017 at 16:00 Type: Parallel Session: Algorithms and Machines Track: Algorithms and Machines Several parallel machines on which Lattice LQCD applications are being run utilize a new fabric, Intel Omni-Path. We present an overview of Omni-Path, comparing it to the well-known competitor InfiniBand. In the process of adding support for Omni-Path to our communication library pMR we discovered several insights which we discuss along some general usage recommendations. We substantiate our findi ... More Presented by Mr. Peter GEORG on 19 Jun 2017 at 17:00 Type: Parallel Session: Software Development Track: Software Development A code for the simulation of QCD+QED with C* boundary conditions is presented. This code is based on openQCD-1.6, from which it inherits the core features that ensure its efficiency: the locally-deflated SAP-preconditioned GCR solver, the twisted-mass frequency splitting of the fermion action, the multilevel integrator, the 4th order OMF integrator, the SSE/AVX intrinsics, etc. The photon field is ... More Presented by Dr. Agostino PATELLA on 22 Jun 2017 at 17:10 Type: Parallel Session: Software Development Track: Software Development A code for the simulation of QCD+QED with C* boundary conditions is presented. This code is based on openQCD-1.6, from which it inherits the core features that ensure its efficiency: the locally-deflated SAP-preconditioned GCR solver, the twisted-mass frequency splitting of the fermion action, the multilevel integrator, the 4th order OMF integrator, the SSE/AVX intrinsics, etc. The photon field is ... More Presented by Marina KRSTIC MARINKOVIC on 22 Jun 2017 at 17:30 Type: Poster Session: Poster Session We present an update of BQCD, our Hybrid-Monte-Carlo program for simulating lattice QCD. BQCD is one of the main production codes of the QCDSF collaboration and is used by CSSM and in some Japanese finite temperature and finite density projects. Since the first publication of the code at Lattice 2010 the program has been extended in various ways. New features of the code include: dynamical ... More Presented by Hinnerk STÜBEN on 20 Jun 2017 at 19:30 Type: Parallel Session: Nonzero Temperature and Density Track: Nonzero Temperature and Density In QCD above the deconfinement temperature there exists an Anderson transition in the fermion spectrum from localized to delocalized modes. We investigate whether the same holds for nonlinear sigma models. In particular we study the spectra of fermions coupled to (quenched) CP(N-1) configurations at high temperatures. We compare results in two and three space-time dimensions: in two dimensio ... More Presented by Mr. jacob WELLNHOFER on 19 Jun 2017 at 15:50 Type: Parallel Session: Theoretical Developments Track: Theoretical Developments We study a tensor network formulation of the two dimensional lattice$\mathcal{N}=1$Wess$\unicode{x2013}$Zumino model with Wilson derivatives for fermions and bosons. The tensor renormalization group allows us to compute the partition function without the sign problem, and basic ideas to obtain a tensor network for both fermion and scalar boson systems were already given in previous works. While ... More Presented by Mr. Ryo SAKAI on 23 Jun 2017 at 18:10 Type: Parallel Session: Nonzero Temperature and Density Track: Nonzero Temperature and Density We study the low temperature region of the$T-\mu_B$phase diagram of QCD with$N_f$=2 and 4 flavors of staggered fermions with the density of states method. We generate configurations at finite isospin chemical potential using different observables as constrained quantities: the gauge action and the pion condensate. Presented by Mr. Csaba TOROK on 20 Jun 2017 at 16:20 Type: Poster Session: Poster Session The QUDA library for Lattice QCD on NVIDIA GPUs will be around for 10 years in 2018. In this time QUDA has developed from an acceleration library for solvers to a framework for developing QCD simulations. It support many different fermion discretizations, and features many algorithms like Adaptive Multigrid, deflation and Block Krylov space methods, using various techniques such as mixed-precision ... More Presented by Dr. Mathias WAGNER on 20 Jun 2017 at 20:30 Type: Parallel Session: Theoretical Developments Track: Theoretical Developments Recently, the Atiyah-Patodi-Singer(APS) index theorem attracts attention for understanding physics on the surface of materials in topological phases. Although it is widely applied to physics, the mathematical setup in original APS index theorem is too abstract and general (allowing non-trivial metric and so on) and also the connection bewteen the APS boundary condition and the physical boundary co ... More Presented by Prof. Tetsuya ONOGI on 23 Jun 2017 at 15:40 Type: Parallel Session: Software Development Track: Software Development The process of generating ensembles of gauge configurations (and measuring various observables over them) can be tedious and error-prone when done "by hand". In practice, most of this procedure can be automated with the use of a workflow manager. We discuss how this automation can be accomplished using Taxi, a minimal workflow manager built for generating lattice data. We present a case study d ... More Presented by Daniel HACKETT on 23 Jun 2017 at 17:50 Type: Parallel Session: Hadron Structure Track: Hadron Structure The auxiliary field approach, where one introduces a field whose propagator is the gauge connection along a chosen path, has been used to study renormalization of extended operators in the continuum. If we restrict the paths to straight lines along the axes, the theory can be discretized with an action similar to lattice heavy-quark effective theory in the static limit. Using this theory, extended ... More Presented by Dr. Jeremy GREEN on 20 Jun 2017 at 15:00 Type: Parallel Session: Nonzero Temperature and Density Track: Nonzero Temperature and Density We investigate the axial$U(1)$symmetry breaking above the critical temperature in 2-flavor lattice QCD whose ensembles are generated with Mobius domain-wall fermions. We will discuss the temperature and quark mass dependence of$U(1)_A$susceptibility extracted from the spectra of overlap Dirac eigenmodes. The behavior of$U(1)_A$susceptibility is compared with that of topological susceptib ... More Presented by Dr. Kei SUZUKI on 19 Jun 2017 at 14:30 Type: Plenary Session: Plenary Session - V First I will review the QCD theta problem and the Peccei-Quinn solution, with its new particle, the axion. I will review the possibility of the axion as dark matter. If PQ symmetry was restored at some point in the hot early Universe, it should be possible to make a definite prediction for the axion mass if it constitutes the Dark Matter. I will describe progress on one issue needed to mak ... More Presented by Prof. Guy MOORE on 22 Jun 2017 at 09:00 Type: Plenary Session: Plenary Session - III The LHCb collaboration has provided a plethora of precise measurements of flavour observables in the last years. In the B sector some of these results show consistent deviations from the Standard Model with a clear tendency to specific New Physics scenarios. B decay anomalies are found in particular related to lepton flavour universality and angular observables in flavour-changing-neutral-current ... More Presented by Arantza OYANGUREN on 20 Jun 2017 at 09:00 Type: Parallel Session: Weak Decays and Matrix Elements Track: Weak Decays and Matrix Elements An update on the RBC-UKQCD measurement of BSM kaon mixing, simulated in nf=2+1 QCD with domain wall fermions at the physical quark masses. Presented by Ms. Julia KETTLE on 21 Jun 2017 at 11:30 Type: Parallel Session: Software Development Track: Software Development Numerical QCD is often extremely resource demanding and it is not rare to run hundreds of simulations at the same time. Each of these typically requires a job-script file as well as an input file with the physical parameters for the application to be run. Moreover, it is often necessary to resume a simulation either because it crashed or simply because the accumulated statistics is not sufficien ... More Presented by Dr. Alessandro SCIARRA on 23 Jun 2017 at 18:50 Type: Parallel Session: Hadron Spectroscopy and Interactions Track: Hadron Spectroscopy and Interactions The introduction of a uniform background magnetic field breaks three-dimensional spatial symmetry for a charged particle. This makes standard quark operators inefficient at isolating the nucleon correlation function at nontrivial field strengths. We introduce novel quark operators constructed from the two-dimensional Landau modes that describe a charged particle on a finite lattice. These Landau ... More Presented by Dr. Waseem KAMLEH on 19 Jun 2017 at 15:50 Type: Parallel Session: Hadron Spectroscopy and Interactions Track: Hadron Spectroscopy and Interactions Hyperon-nucleon and hyperon-hyperon interactions are important in studying the properties of hypernuclei in hypernuclear physics. However, unlike the nucleons which are quite stable, hyperons are unstable so that the direct scattering experiments are difficult, which leads to the large uncertainty in the phenomenological determination of hyperon potentials. I ... More Presented by Prof. Noriyoshi ISHII on 22 Jun 2017 at 15:40 Type: Parallel Session: Hadron Spectroscopy and Interactions Track: Hadron Spectroscopy and Interactions We present our recent results of baryon interactions with strangeness$S=-1$based on Nambu-Bethe-Salpeter (NBS) correlation functions calculated from lattice QCD with almost physical quark masses corresponding to$(m_\pi,m_K)\approx(146,525)$MeV and large volume$(La)^4=(96a)^4\approx$(8.1 fm)$^4$. In order to perform a comprehensive study of baryon interactions[1], a large number of NBS correl ... More Presented by Dr. Hidekatsu NEMURA on 22 Jun 2017 at 16:20 Type: Parallel Session: Hadron Spectroscopy and Interactions Track: Hadron Spectroscopy and Interactions First-principles determination of baryon interactions plays a crucial role to build a bridge between particle, nuclear and astro-physics. The first LQCD calculation of baryon forces with (almost) physical quark masses (m_pi=146 MeV) is in progress, where the interactions are extracted from Nambu-Bethe-Salpeter (NBS) correlators by the time-dependent HAL QCD method. In this talk, we give a brief ov ... More Presented by Takumi DOI on 22 Jun 2017 at 15:20 Type: Parallel Session: Hadron Structure Track: Hadron Structure Magnetic moments of the octet baryons are computed using lattice QCD in background magnetic fields, including the first treatment of the magnetically coupled$\Sigma^0$-$\Lambda$system. Although the computations are performed for relatively large values of the up and down quark masses, we gain new insight into the symmetries and relations between magnetic moments by working at a three-flavor mass ... More Presented by Brian TIBURZI on 21 Jun 2017 at 10:00 Type: Parallel Session: Hadron Structure Track: Hadron Structure We have developed a new way of computing three-point functions. This is based on a factorization with open spin- (and to some extent flavour-) indices that allows us to generate these simultaneously for many different initial and final states and momenta, with little computational overhead. This factorization as well as its implementation will be explained. A new library has been written to ef ... More Presented by Mr. Marius LÖFFLER on 21 Jun 2017 at 12:30 Type: Poster Session: Poster Session We present preliminary simulation results of the lattice sine-Gordon model which show evidence of the Berezinskii-Kosterlitz-Thouless phase transition. Our simulation algorithm uses Fourier accelerated hybrid Monte Carlo techniques to reduce autocorrelations. The BKT transition involves a topological phase, with no local order parameter, driven by the physics of topological defects. The sine-Gord ... More Presented by Prof. Joel GIEDT on 20 Jun 2017 at 19:30 Type: Parallel Session: Hadron Structure Track: Hadron Structure Recently, an interquark potential is derived from Bethe-Salpeter(BS) amplitudes of charmonium ground state by Kawanai and Sasaki. The quark potential models with an energy-independent central potential have been successful for understanding the conventional charmonium states especially below the open charm threshold. As one might consider, however, the interquark potential is in general energy- ... More Presented by Mr. Kazuki NOCHI on 20 Jun 2017 at 18:50 Type: Parallel Session: Physics Beyond the Standard Model Track: Physics Beyond the Standard Model We study the quantum corrections to the real-time evolution of the BFSS matrix model, which is holographically dual to a system of interacting D0 branes. Classical chaos in this system has been interpreted as a scrambling of information due to formation of a black hole. We demonstrate that fermions in this model, simulated within the classical-statistical (CSFT) approximation, lead to an instabili ... More Presented by Dr. Pavel BUIVIDOVICH on 22 Jun 2017 at 18:50 Type: Parallel Session: Algorithms and Machines Track: Algorithms and Machines We report recent efforts by CLS to generate an ensemble with physical light- and strange-quark masses in a lattice volume of$96^3x192$at$\beta=3.55$corresponding to a lattice spacing of 0.064fm. This ensemble is being generated as part of the CLS 2+1 flavor effort with improved Wilson fermions. Our simulations currently cover 5 lattice spacings ranging from 0.039fm to 0.086fm at various pion m ... More Presented by Dr. Daniel MOHLER on 20 Jun 2017 at 18:10 Type: Parallel Session: Standard Model Parameters and Renormalization Track: Standard Model Parameters and Renormalization$B_{K}$is a parameter which is related with the Kaon mixing and is one of the targets of Lattice QCD. Naive calculation of$B_{K}$with the Wilson fermion is difficult because the chiral symmetry is explicitly broken. In this talk we shall present on our calculation of$B_{K}$with the Wilson fermion by applying the gradient flow method both to the gauge and quark fields. Our study is based o ... More Presented by Mr. Asobu SUZUKI on 21 Jun 2017 at 12:50 Type: Parallel Session: Weak Decays and Matrix Elements Track: Weak Decays and Matrix Elements We present preliminary results of the calculation of$\bar{B} \rightarrow D^\ast \ell \bar{\nu}$form factor at zero recoil. We use$N_f=2+1+1$MILC HISQ ensembles. The charm and bottom quarks are implemented using the Oktay-Kronfeld (OK) action. For the light spectator quark, we use the HISQ action. We also report a recent progress in determining the critical hopping parameter$\kappa_\text{cri ... More
Presented by Mr. Sungwoo PARK on 19 Jun 2017 at 17:20
Type: Parallel Session: Hadron Spectroscopy and Interactions
Track: Hadron Spectroscopy and Interactions
Achieving long plateaus in multibaryon systems is challenging because excited states contaminate the signal at early times and the signal is destroyed by noise at late times---ensuring there is enough time in between these two systematic effects is critical. I will explain how optimizing single-baryon observables can yield substantial improvements to multibaryon systems, dramatically extending ... More
Presented by Dr. Evan BERKOWITZ on 22 Jun 2017 at 17:50
Type: Parallel Session: Nonzero Temperature and Density
Track: Nonzero Temperature and Density
In the worldline formulation the particle number of a lattice quantum field theory assumes an elegant topological form: it is the winding number of the worldlines around the compactified time direction. In a numerical worldline simulation one can implement the canonical ensemble by using only updates that preserve the winding number and thus the number of particles. We explore the idea of a canoni ... More
Presented by Mr. Oliver ORASCH on 22 Jun 2017 at 16:00
Type: Parallel Session: Hadron Structure
Track: Hadron Structure
I will present higher loop order results on a number of calculations within Chiral perturbation Theory. 1) Preliminary results on a three-loop calculation of the pion mass and decay constant in two-flavour ChPT. For the pion mass all needed auxiliary parameters can probably be determined from lattice calculations of $\pi\pi$-scattering. 2) (The main part) Two-loop results at finite volume f ... More
Presented by Prof. Johan BIJNENS on 22 Jun 2017 at 16:00
Type: Parallel Session: Applications Beyond QCD
Track: Applications Beyond QCD
Many groups are now interested in combining QCD and QED on the lattice. Simulations with massless photons bring new infra-red and finite size issues. When we simulate an electrically charged hadron on the lattice we do several odd things. We create charged particles from the vacuum, violating conservation of charge. We use periodic boundary conditions, which don't allow a net outward elec ... More
Presented by Paul RAKOW on 23 Jun 2017 at 17:50
Type: Poster Session: Poster Session
The one-dimensional extended t-V model on a lattice describes fermions with repulsive interactions of finite range and exhibits a quantum phase transition between a Luttinger liquid conducting phase and a Mott insulating phase. Its properties make it useful in the description of candidate materials for Mott transistor devices. It is known that by tailoring the potential energy of the insulating sy ... More
Presented by Dr. Marcin SZYNISZEWSKI on 20 Jun 2017 at 20:30
Type: Parallel Session: Weak Decays and Matrix Elements
Track: Weak Decays and Matrix Elements
I will review the domain wall charm physics program of the RBC and UKQCD collaborations using physical pion masses. After a brief recap of our previous results ($f_D$ and $f_{D_s}$), I will present our current set-up and present a status update of a number of observables.
Presented by Justus Tobias TSANG on 20 Jun 2017 at 18:50
Type: Parallel Session: Weak Decays and Matrix Elements
Track: Weak Decays and Matrix Elements
I present a high-precision lattice QCD calculation of $\Lambda_c\to\Lambda$ form factors and a determination of the CKM matrix element $|V_{cs}|$ from $\Lambda_c\to\Lambda \ell^+\nu_\ell$ decays. I will also show preliminary results for $\Lambda_c \to p$ form factors, which are relevant for the rare charm decays $\Lambda_c \to p \ell^+\ell^-$.
Presented by Prof. Stefan MEINEL on 20 Jun 2017 at 17:30
Type: Parallel Session: Weak Decays and Matrix Elements
Track: Weak Decays and Matrix Elements
We present results for the decay constants $f_B$ and $f_{B_s}$ and update our earlier determinations of $f_D$ and $f_{D_s}$. We employ HISQ ensembles with 2+1+1 flavors generated at six lattice spacings, including five with physical light-quark masses. Calculations are carried out with several heavy valence-quark masses ranging from near charm to bottom (at the finest lattice spacing). In additio ... More
Presented by Javad KOMIJANI on 20 Jun 2017 at 15:40
Type: Parallel Session: Hadron Spectroscopy and Interactions
Track: Hadron Spectroscopy and Interactions
Comparison of radial excitation energies to masses show that the velocity of b quark is very non-relativistic in bottomonium states. In a mixed system like charmed B meson, the b quark has less velocity than it has in bottomonium states and in strange B meson it is even slower. So one can use NRQCD for the b quark in those systems. Using overlap action for the s and c quarks and NRQCD for b q ... More
Presented by Mr. Protick MOHANTA on 21 Jun 2017 at 09:40
Type: Parallel Session: Hadron Structure
Track: Hadron Structure
Extending the SU(3) flavour symmetry breaking expansion from up, down and strange sea quark masses to partially quenched valence quark masses allows an extrapolation to the charm quark mass. This approach leads to a determination of charmed quark hadron masses and decay constants. Initial results are encouraging and demonstrate the potential of the procedure.
Presented by Dr. Roger HORSLEY on 21 Jun 2017 at 10:40
Type: Poster Session: Poster Session
Lattice simulation of charmonium resonances with non-zero momentum provides additional information on the relevant two-meson scattering matrices. However, the reduced rotational symmetry in a moving frame renders a number of states with different J^P in the same lattice irreducible representation. The identification of the underlying spin and parity for these states is particularly important fo ... More
Presented by Prof. Sasa PRELOVSEK on 20 Jun 2017 at 19:30
Type: Parallel Session: Hadron Spectroscopy and Interactions
Track: Hadron Spectroscopy and Interactions
Many experiments have found evidence of charmonium-like states that do not fit into conventional models of quark-antiquark mesons. Non-perturbative insight provided by lattice simulations can help in understanding the properties of those states. The computation of single and multiparticle correlators is the main challenge of the numerical investigation of unstable states on the lattice. We extract ... More
Presented by Dr. Stefano PIEMONTE on 23 Jun 2017 at 16:20
Type: Parallel Session: Hadron Spectroscopy and Interactions
Track: Hadron Spectroscopy and Interactions
There has been a lot of theoretical effort to unmask the pentaquark candidates, the $P_c^+$, since they were reported by LHCb collaboration in 2015. However, lack of knowledge in charmed-hadron interactions seems to be causing controversy on this issue; some argue that they are loosely-bound meson-baryon state, while others consider them as tightly-bound states, threshold cusps, and so forth. In ... More
Presented by Mr. Takuya SUGIURA on 23 Jun 2017 at 15:20
Type: Parallel Session: Chiral Symmetry
Track: Chiral Symmetry
In previous work [1] we showed that the chiral condensate of one flavor QCD shows a Silver Blaze phenomenon when the quark mass crosses $m=0$: The chiral condensate remains constant while the quark mass crosses the spectrum of the Dirac operator which is dense on the imaginary axis. This behavior is explained in terms of exponentially large cancellations between contributions from the zero mod ... More
Presented by Prof. Jacobus VERBAARSCHOT on 22 Jun 2017 at 17:10
Type: Parallel Session: Hadron Spectroscopy and Interactions
Track: Hadron Spectroscopy and Interactions
Recently, phase shift data for the $\rho$-meson have been extracted from several $N_f = 2 + 1$ lattice simulations for diff erent pion masses. We analyze the lattice data sets with Unitarized Chiral Pertubation Theory. Chiral extrapolations are performed to postdict experimental phase shift data, and also compared with the ones obtained from the analysis of $N_f = 2$ lattice data. The low-energy ... More
Presented by Dr. Raquel MOLINA on 20 Jun 2017 at 18:30
Type: Parallel Session: Nonzero Temperature and Density
Track: Nonzero Temperature and Density
Lattice simulations for (2+1)-flavor QCD demonstrated that the quark mass is one of the important parameters responsible for the (inverse)-magnetic catalysis. In this talk we will discuss the dependence of chiral condensates and susceptibilities on the magnetic field in three flavor QCD in the regime of the first order phase transition. The lattice simulations were performed using standard stagger ... More
Presented by Dr. Akio TOMIYA on 19 Jun 2017 at 15:30
Type: Parallel Session: Physics Beyond the Standard Model
Track: Physics Beyond the Standard Model
We study the phase structure of SU(4) gauge theory with dynamical quarks in both the fundamental and two-index antisymmetric representations. Such "multi-representation" theories have been speculated to exhibit separated phase transitions, but we determine from lattice results that the chiral transitions occur simultaneously with each other and with the confinement transition. We investigate th ... More
Presented by Daniel HACKETT on 19 Jun 2017 at 15:50
Type: Plenary Session: Closing Remarks
Closing remarks
Presented by Elvira GAMIZ-SANCHEZ on 24 Jun 2017 at 12:30
Type: Parallel Session: Algorithms and Machines
Track: Algorithms and Machines
The RBC and UKQCD Collaborations are generating coarse lattices with volumes of (4.8 fm)$^3$, (6.4 fm)$^3$ and (9.6 fm)$^3$. These lattices have physical values for the light and strange quark masses and $1/a = 1.0$ GeV. An important feature of these lattices is that measured observables show very small $O(a^2)$ corrections. Physical properties of these lattices will be presented, along with de ... More
Presented by Robert MAWHNNEY on 20 Jun 2017 at 17:30
Type: Parallel Session: Nonzero Temperature and Density
Track: Nonzero Temperature and Density
We study correlation functions of a static quark antiquark pair in spatial separation in 2+1 flavor QCD in order to better understand the nature of color screening at high temperatures. We performed lattice calculations in a wide temperature range $140$ MeV $\leq T \leq 5.8$ GeV using the using the highly improved staggered quark (HISQ) action and several lattice spacings to control discretizatio ... More
Presented by Dr. Johannes WEBER on 20 Jun 2017 at 16:00
Type: Poster Session: Poster Session
We present colour field density profiles for some of the first SU(3) gluonic excitations of the flux tube in the presence of a static quark-antiquark pair. The results are obtained from a large set of gluonic operators.
Presented by Pedro BICUDO on 20 Jun 2017 at 19:30
Type: Parallel Session: Nonzero Temperature and Density
Track: Nonzero Temperature and Density
In application of the complex Langevin method to finite density QCD at low temperature, the singular-drift problem occurs due to the appearance of near-zero eigenvalues of the Dirac operator. In order to avoid this problem, we proposed to deform the Dirac operator in such a way that the near-zero eigenvalues do not appear and to extrapolate the deformation parameter to zero from the available data ... More
Presented by Dr. Yuta ITO on 20 Jun 2017 at 17:50
Type: Parallel Session: Hadron Spectroscopy and Interactions
Track: Hadron Spectroscopy and Interactions
We investigate a systematic error coming from higher excited state contributions in the binding energy of light nucleus by comparing two different source calculations with the exponential and wall sources. Since it is hard to obtain a clear signal of the wall source correlation function in a plateau region, we employ a large quark mass as the pion mass is 0.8 GeV in quenched QCD. We discuss t ... More
Presented by Takeshi YAMAZAKI on 22 Jun 2017 at 18:10
Type: Parallel Session: Nonzero Temperature and Density
Track: Nonzero Temperature and Density
We have extended our CLE simulations of lattice QCD at a finite quark-number chemical potential, $\mu$, on a $12^4$ lattice at $\beta=6/g^2=5.6$ to a weaker coupling, $\beta=5.7$, and larger, $16^4$, lattice. Limitations of the method and choice of lattice fermions are discussed as are possible improvements.
Presented by Dr. Donald SINCLAIR on 20 Jun 2017 at 18:10
Type: Parallel Session: Nonzero Temperature and Density
Track: Nonzero Temperature and Density
We study QCD at finite density and low temperature by using the complex Langevin method. We employ the gauge cooling to control the unitarity norm and introduce a deformation parameter in the Dirac operator to avoid the singular drift problem. The reliability of the obtained results are judged by the probability distribution of the magnitude of the drift term. By extrapolating the reliable results ... More
Presented by Dr. Shinji SHIMASAKI on 20 Jun 2017 at 17:30
Type: Parallel Session: Standard Model Parameters and Renormalization
Track: Standard Model Parameters and Renormalization
We compute, up to order $g^4$ in perturbation theory, the fermionic contribution to the strong coupling $\alpha_{qq}$ extracted from the static force in Lattice QCD. To this aim, we calculate perturbatively Wilson loops using a simplified version of QCD: a SU(3) gauge theory coupled to two degenerate quarks. In particular, we have considered the following discretization: Wilson's plaquette ga ... More
Presented by Mr. Salvatore CALI on 21 Jun 2017 at 09:20
Type: Parallel Session: Hadron Spectroscopy and Interactions
Track: Hadron Spectroscopy and Interactions
We compute hybrid static potentials in SU(3) lattice gauge theory. We present a method to automatically generate a large set of suitable creation operators with defined quantum numbers from elementary building blocks. We show preliminary results for several channels and discuss, which structures of the gluonic flux tube seem to be realized by the ground states in these channels.
Presented by Mr. Christian REISINGER on 23 Jun 2017 at 16:00
Type: Poster Session: Poster Session
Parton distribution functions provide an important insight into the inner structure of hadrons, by giving information on the momentum and spin distribution of partons. Extracting parton distribution functions (PDFs) directly from Lattice QCD has been thought impossible, since they are given in terms of non-local light cone correlations in Minkowski space-time and light-like distances are not acce ... More
Presented by Ms. Aurora SCAPELLATO on 20 Jun 2017 at 19:30
Type: Poster Session: Poster Session
Track: Nonzero Temperature and Density
We calculate the entropy of SU(3) Yang-Mills theory in a moving frame using the Symanzik improved action. By using shifted boundary conditions a moving frame can be realized on the lattice. In this setting the momentum density and the renormalization constant of the offdiagonal elements of the energy-momentum tensor are computed. The results are then used to compute the entropy density.
Presented by Mr. Dominik LAUBACH on 20 Jun 2017 at 20:30
Type: Parallel Session: Hadron Structure
Track: Hadron Structure
I will discuss briefly recent changes in the methodology of computing the baryon EDM on a lattice. The associated correction substantially reduces presently existing lattice values for the proton and neutron theta-induced EDMs, so that even the most precise previous lattice results become consistent with zero. On one hand, this change removes previous disagreements between these lattice results an ... More
Presented by Prof. Sergey SYRITSYN on 21 Jun 2017 at 09:00
Type: Parallel Session: Nonzero Temperature and Density
Track: Nonzero Temperature and Density
We use a dual worldline representation to study the relativistic Bose gas at finite density. At low temperature we identify the thresholds for one- and two-particle condensation. We study these thresholds as a function of the spatial size and use the Lüscher formula to determine the scattering length.
Presented by Mr. Mario GIULIANI on 22 Jun 2017 at 16:20
Type: Parallel Session: Physics Beyond the Standard Model
Track: Physics Beyond the Standard Model
We study the phase structure of an SU(4) gauge theory with dynamical fermions in both the fundamental and the two-index antisymmetric representations. Our lattice calculations show the existence of a first-order confinement transition. Although the presence of two different representations opens up the possibility of two separate confinement transitions, our results are consistent with a single ph ... More
Presented by Mr. Venkitesh AYYAR on 19 Jun 2017 at 15:30
Type: Poster Session: Poster Session
We present updated results of the infrared behavior of the SU(2) model with 6 and 8 fundamental representation fermions. We use the gradient flow method with the Schrödinger functional boundary conditions to measure the running of the coupling in these theories and find fixed points on both. We also measure the mass anomalous dimension from these configurations and compare those results to mass a ... More
Presented by Mr. Viljami LEINO on 20 Jun 2017 at 20:30
Type: Parallel Session: Hadron Structure
Track: Hadron Structure
We present results on the isovector and isoscalar nucleon axial form factors including disconnected contributions. The light disconnected quark loops have been computed using exact deflation, while the strange and the charm quark loops have been evaluated using the truncated solver method. Techniques such as the summation and the two-state fits have been employed to control the excited states cont ... More
Presented by Dr. Kyriakos HADJIYIANNAKOU on 19 Jun 2017 at 15:30
Type: Parallel Session: Hadron Structure
Track: Hadron Structure
We present lattice QCD calculations of the hadronic light-by-light (HLbL) contribution to the muon anomalous magnetic moment with physical masses at two different lattice spacings. The calculation includes all connected diagrams and the leading, quark-line-disconnected diagrams. Our first calculation has been performed on the $48^3\times 96$ ensemble generated with physical quark masses, $a^{-1}= ... More Presented by Thomas BLUM on 23 Jun 2017 at 17:10 Type: Parallel Session: Nonzero Temperature and Density Track: Nonzero Temperature and Density For the investigation of in-medium modifications of quarkonia and for determining heavy quark diffusion transport coefficients, correlation functions of heavy mesons play a crucial role. For the first time we performed a continuum extrapolation of charmonium correlators in the vector and pseudoscalar channels based on non-perturbatively clover improved Wilson fermions in quenched lattice QCD. We p ... More Presented by Mr. Hauke SANDMEYER on 19 Jun 2017 at 17:00 Type: Parallel Session: Nonzero Temperature and Density Track: Nonzero Temperature and Density We carry out the continuum extrapolation of the critical point for finite temperature QCD with Nf=3 using several temporal lattice sizes N_t=4, 6, 8 and 10. We employ the Iwasaki gauge action and non-perturbatively O(a) improved Wilson fermions. We estimate the critical pseudo-scalar meson mass and temperature. Presented by Dr. SHINJI TAKEDA on 20 Jun 2017 at 15:00 Type: Parallel Session: Algorithms and Machines Track: Algorithms and Machines In recent years adaptive smoothed aggregation algebraic multigrid ($\alpha$SA-AMG) methods have been developed and subsequently adapted for use in lattice quantum chromodynamics (QCD). The purpose of these efforts has been to reduce the critical slowdown that occurs in lattice QCD algorithms when working on state-of-the-art problems. Convergence theorems can establish the robustness of such meth ... More Presented by Mr. Edward WHITE, JR. on 19 Jun 2017 at 15:30 Type: Parallel Session: Theoretical Developments Track: Theoretical Developments The positivity of the Boltzmann weight, needed for its probabilistic interpretation and for the application of the Monte Carlo method is absent for theories with complex actions. We propose avoiding the latter problem substituting Monte Carlo simulations by computations with convergent 'non-perturbative' expansions. We discuss constructions of such expansions and first numerical results on the exa ... More Presented by Dr. Vasily SAZONOV on 22 Jun 2017 at 18:10 Type: Parallel Session: Hadron Spectroscopy and Interactions Track: Hadron Spectroscopy and Interactions I will discuss recent coupled-channel scattering calculations from the Hadron Spectrum Collaboration. Utilising the variational method with large bases of operators, including those that resemble q-qbar and meson-meson like constructions, many energy levels can be extracted. These spectra are then used with the coupled-channel extensions of Lüscher's finite volume formalism, to determine the infi ... More Presented by David WILSON on 19 Jun 2017 at 14:50 Type: Parallel Session: Nonzero Temperature and Density Track: Nonzero Temperature and Density We investigate the critical endline of the finite temperature phase transition of QCD away from the SU(3)-flavor symmetric point at zero chemical potential. We employ the renormalization-group improved Iwasaki gauge action and non-perturbatively$O(a)$-improved Wilson-clover fermion action. The critical endline is determined by using the intersection point of kurtosis, employing the multi-parame ... More Presented by Dr. Yoshifumi NAKAMURA on 20 Jun 2017 at 15:20 Type: Parallel Session: Nonzero Temperature and Density Track: Nonzero Temperature and Density We studied the critical endpoint of 4-flavor QCD at finite temperature and zero chemical potential. Our lattice QCD simulations have been performed with the Iwasaki gauge and the non-perturbatively$O(a)$-improved Wilson fermion actions on lattices with$N_t$= 4, 6 and 8. We determined the critical endpoint from an intersection point of kurtosis of the chiral condensate with three different volum ... More Presented by Dr. Hiroshi OHNO on 21 Jun 2017 at 11:30 Type: Parallel Session: Hadron Structure Track: Hadron Structure In local quantum field theories, conserved current operators are obtained by Neother’s theorem. However, this is not the case with effective theories with non-local interactions which are obtained after some of the degrees of freedom are integrated out. Consider for a instance, a system made of a proton and a neutron interacting through one pion exchange potential. The electromagnetic charge i ... More Presented by Kai WATANABE on 20 Jun 2017 at 18:30 Type: Parallel Session: Weak Decays and Matrix Elements Track: Weak Decays and Matrix Elements We report preliminary results on semileptonic form factors of$B_c\rightarrow \eta_c l\nu$and$B_c\rightarrow J/\psi l\nu$decays as well as the decay constant of$B_c$meson. For the charm quark we use overlap fermions whereas a non-relativistic formulation with improved coefficients is utilized for the bottom quark on a background of three 2+1+1 flavours HISQ lattice ensembles generated by the ... More Presented by Prof. Nilmani MATHUR on 19 Jun 2017 at 17:40 Type: Parallel Session: Standard Model Parameters and Renormalization Track: Standard Model Parameters and Renormalization We study the effective theory of decoupling of a charm quark at low energies. We do this by simulating a model, QCD with two mass-degenerate charm quarks. At leading order the effective theory is a pure gauge theory. We compare the mass dependence of hadronic scales to the prediction based on perturbative matching of the gauge couplings. By computing ratios of hadronic scales we have direct acces ... More Presented by Prof. Francesco KNECHTLI on 21 Jun 2017 at 10:20 Type: Parallel Session: Nonzero Temperature and Density Track: Nonzero Temperature and Density We study spatial isovector meson correlators in Nf=2 QCD with dynamical domain-wall fermions on the 32^3x8 lattices at temperatures T=170-380MeV with various quark masses. We measure the correlators of spin-one operators including vector ("V", 1--), axial-vector ("AV",1++), tensor ("T", 1--) and axial-tensor ("AT", 1+-). At temperatures above T_c, we observe a degeneracy of the correlators in th ... More Presented by Mr. Christian ROHRHOFER on 21 Jun 2017 at 12:30 Type: Parallel Session: Applications Beyond QCD Track: Applications Beyond QCD Entanglement entropy provides a quantitative measure of quantum purity in a quantum system. In this work, lattice methods are used to exactly solve non-relativistic, interacting few-body systems in one dimension. Focus is placed on the time-dependent dynamics of the entanglement entropy, particularly around externally driven resonances. The entanglement entropy is found to provide a robust indicat ... More Presented by Mr. Joshua MCKENNEY on 23 Jun 2017 at 16:20 Type: Plenary Session: Plenary Session - VII We present a determination of the strong coupling constant in the MS-bar scheme at the Z-mass scale, using low energy quantities, namely pion/kaon decay constants and masses, as experimental input. The computation employs two different massless finite volume renormalization schemes to non-perturbatively trace the scale dependence of the respective running couplings from a scale of about 200 MeV ... More Presented by Dr. Tomasz KORZEC on 23 Jun 2017 at 10:45 Type: Parallel Session: Software Development Track: Software Development QUDA is an increasingly popular GPU library for both accelerating legacy lattice QCD applications and, having also evolved into a framework in its own right, for directly deploying QCD simulations. Recent work has focused on simplifying the framework to lower the barrier of entry to extending QUDA for new algorithms and methods. In this talk we describe the QUDA framework, with worked examples o ... More Presented by Dr. Kate CLARK on 23 Jun 2017 at 15:00 Type: Parallel Session: Theoretical Developments Track: Theoretical Developments We have developed Grassmann higher order tensor renormalization group (GHOTRG) to analyze higher dimensional fermionic systems. We first apply it to three-dimensional free Wilson fermions as a benchmark to check its effectiveness. The results of the free energy and the fermion Green functions are presented in comparison with the exact values. We also briefly discuss to what extent the results are ... More Presented by Mr. Yusuke YOSHIMURA on 21 Jun 2017 at 12:50 Type: Parallel Session: Standard Model Parameters and Renormalization Track: Standard Model Parameters and Renormalization We compute the Dirac spectral density of QCD in a wide range of eigenvalues by using the stochastic approach. The spectral density at relatively high eigenvalues can be used to extract the mass anomalous dimension. We use 2+1-flavor lattice ensembles generated with Mobius domain-wall fermion at three lattice spacings (a=0.083, 0.055, 0.044 fm) to estimate the continuum limit. The discretization ef ... More Presented by Mr. Katsumasa NAKAYAMA on 21 Jun 2017 at 09:00 Type: Parallel Session: Vacuum Structure and Confinement Track: Vacuum Structure and Confinement Recently, it is suggested that a quark number holonomy defined from the quark number densities at finite imaginary chemical potential is strongly related to the confinement-deconfinement transition [1]. We investigate the quark number density at zero and finite imaginary chemical potential in terms of the eigenmodes of the Dirac operator, which are strongly related to chiral symmetry breaking. ... More Presented by Dr. Takahiro DOI on 20 Jun 2017 at 16:00 Type: Parallel Session: Applications Beyond QCD Track: Applications Beyond QCD The detection of the (semi)metal-insulator phase transition can be extremely difficult if the local order parameter which characterizes the ordered phase is unknown. In some cases, it is even impossible to define a local order parameter: the most prominent example of such system is the spin liquid state. This state was proposed to exist in the Hubbard model on the hexagonal lattice in a region bet ... More Presented by Dr. Maksim ULYBYSHEV on 23 Jun 2017 at 15:20 Type: Parallel Session: Weak Decays and Matrix Elements Track: Weak Decays and Matrix Elements We investigate the dispersion relation of Mobius domain-wall fermions in free field theory at finite$L_s$. We find that the quark propagator constructed from the domain-wall fermion operator has$L_s-1$extra poles as well as the pole which realizes the physical quark in the continuum limit. The unphysical contribution of these extra poles could be significant when we introduce heavy quarks. In t ... More Presented by Dr. Masaaki TOMII on 23 Jun 2017 at 18:50 Type: Parallel Session: Nonzero Temperature and Density Track: Nonzero Temperature and Density We study spectral properties of charmonia in the vector and pseudoscalar channels at nonzero momenta on quenched lattices focusing on the dispersion relation and the weight of the peak. The spectral functions of charmonia are studied by the maximum entropy method with the lattice Euclidean correlation functions on the anisotropic quenched lattices. The errors of the dispersion relations and th ... More Presented by Prof. Masakiyo KITAZAWA on 19 Jun 2017 at 16:40 Type: Parallel Session: Chiral Symmetry Track: Chiral Symmetry The equivalence between the partition function of QCD in the lowest energy limit and the partition function predicted by the Chiral Random Matrix Theory is well established through the use of the Chiral Perturbation Theory. In particular the ChRMT provides a description of the low-lying eigenvalues of the euclidean Dirac operator. In this work we study, on the lattice, the spectrum of the overlap ... More Presented by Mr. Marco CATILLO on 20 Jun 2017 at 17:50 Type: Parallel Session: Algorithms and Machines Track: Algorithms and Machines RBC/UKQCD has recently finished implementing the exact one flavor algorithm (EOFA), which allows for HMC simulations of single quark flavors without taking a square root of the fermion determinant. In this talk we elaborate on the details of our implementation, including a novel preconditioning scheme for the exact one flavor Dirac operator that has been shown to significantly accelerate the algor ... More Presented by Mr. David MURPHY on 20 Jun 2017 at 18:30 Type: Parallel Session: Vacuum Structure and Confinement Track: Vacuum Structure and Confinement We examine how the vacuum expectation value (average) of double-winding Wilson loops depends on the number of color$N$in the$SU(N)$Yang-Mills theory. In the case where the two loops$C_1$and$C_2$are identical, we derive the exact operator relation which relates the double-winding Wilson loop operator in the fundamental representation to that in the higher dimensional representations dependi ... More Presented by Mr. Ryutaro MATSUDO on 20 Jun 2017 at 15:20 Type: Parallel Session: Nonzero Temperature and Density Track: Nonzero Temperature and Density We present the computation of invariants that arise in the strong coupling expansion of lattice QCD. These invariants allow to perform Monte Carlo simulations of Young Mills Theory and Lattice QCD with staggered fermions in a dual, color singlet representation. This formulation is in particular useful to tame the finite density sign problem. Presented by Dr. Wolfgang UNGER on 21 Jun 2017 at 12:50 Type: Parallel Session: Nonzero Temperature and Density Track: Nonzero Temperature and Density The dual form of the massless Schwinger model on the lattice overcomes the complex action problems from two sources: from a topological term, as well as from non-zero chemical potential, making these physically interesting cases accessible to Monte Carlo simulations. The partition function is represented as a sum over fermion loops, dimers and plaquette-surfaces such that all contributions are ... More Presented by Mr. Daniel GOESCHL on 22 Jun 2017 at 17:10 Type: Parallel Session: Theoretical Developments Track: Theoretical Developments Various approaches to construction of dual formulations of non abelian lattice gauge theories are reviewed. In the case of U(N) LGT we use a theory of the Weingarten functions to construct a dual formulation. In particular, the dual representations are constructed 1) for pure gauge models in all dimensions, 2) in the strong coupling limit for the models with arbitrary number of flavours and 3) for ... More Presented by Dr. Oleg BORISENKO on 21 Jun 2017 at 13:10 Type: Parallel Session: Physics Beyond the Standard Model Track: Physics Beyond the Standard Model First results are presented of a fully dynamical simulation of QCD+Axion for three quark flavors Presented by Prof. Gerrit SCHIERHOLZ on 23 Jun 2017 at 15:00 Type: Parallel Session: Hadron Structure Track: Hadron Structure We utilise a new method to calculate electric dipole moments induced by the strong QCD$\theta$-term and the dimension 6 Weinberg term. The method is based on the gradient flow for gauge fields and is free from renormalisation ambiguities at non-vanishing flow times. The results of the nucleon electric dipole moments are calculated on PACS-CS gauge fields (from japan lattice data grid) using$ ... More
Presented by Dr. Jack DRAGOS on 21 Jun 2017 at 09:20
Type: Parallel Session: Weak Decays and Matrix Elements
Track: Weak Decays and Matrix Elements
We report on the status of our programme to develop a framework for the calculation of electromagnetic corrections to weak decay amplitudes. The $O(1\%)$ precision increasingly being reached in isospin-symmetric QCD calculations necessitates the inclusion of isospin-breaking effects, including electromagnetism, if continuing progress in the determination of the fundamental parameters of the Standa ... More
Presented by Prof. Guido MARTINELLI on 21 Jun 2017 at 10:40
Type: Parallel Session: Hadron Structure
Track: Hadron Structure
We compute the leading $QED$ corrections to the hadronic vacuum polarization (HVP) of the photon, relevant for the determination of leptonic anomalous magnetic moments. We work in the electroquenched approximation and use dynamical $QCD$ configurations generated by the CLS initiative with two degenerate flavors of non-perturbatively O($a$) improved Wilson fermions. We consider $QED_{\rm L}$ and ... More
Presented by Mr. Andrea BUSSONE on 22 Jun 2017 at 18:10
Type: Parallel Session: Hadron Structure
Track: Hadron Structure
We present an update on our determination of the electromagnetic form factors and axial charge of the nucleon from the $N_\mathrm{f} = 2 + 1$ CLS ensembles with increased statistics and an additional finer lattice spacing. We also investigate the impact of O($a$)-improvement of the currents.
Presented by Dr. Georg VON HIPPEL on 19 Jun 2017 at 15:10
Type: Parallel Session: Hadron Structure
Track: Hadron Structure
We present our preliminary result of the electromagnetic form factor of the pion on the large volume configurations $L = 8.1$ fm with $m_\pi = 0.145$ GeV and $m_K = 0.525$ GeV using the stout-smearing clover quark and Iwasaki gauge action at $a^{-1}=2.333$ GeV. From the results at small momentum transfer we determine the mean square charge radius at the physical $m_\pi$ and $m_K$ using the ne ... More
Presented by Junpei KAKAZU on 23 Jun 2017 at 15:00
Type: Parallel Session: Nonzero Temperature and Density
Track: Nonzero Temperature and Density
We measure correlation functions of energy-momentum tensor in Nf=2+1 full QCD at finite temperature by applying the gradient flow method both to the gauge and quark fields. Our main interest is to study the conservation law of the energy-momentum tensor and to extract thermodynamical quantities from the correlation function. We adopt a fine lattice spacing a=0.07 (fm) and cover a wide range of ... More
Presented by Dr. Yusuke TANIGUCHI on 20 Jun 2017 at 15:40
Type: Parallel Session: Nonzero Temperature and Density
Track: Nonzero Temperature and Density
We report the equation of state at finite chemical potential, namely the baryon number density and the baryonic contribution to the pressure, using a resummation of the Taylor expansion. We also report the freezeout conditions for a measure of fluctuations. We examine the major sources of systematic and statistical errors in all of these measurements.
Presented by Prof. Sourendu GUPTA on 23 Jun 2017 at 18:30
Type: Parallel Session: Nonzero Temperature and Density
Track: Nonzero Temperature and Density
We study the energy-momentum tensor and the equation of state as well as the chiral condensate in (2+1)-flavor QCD at the physical point applying the method of Makino and Suzuki based on the gradient flow. Following a strategy of our previous study at a heavier quark mass, we adopt a nonperturbatively O(*a*)-improved Wilson quark action and the renormalization group-improved Iwasaki gauge action a ... More
Presented by Prof. Kazuyuki KANAYA on 21 Jun 2017 at 11:50
Type: Parallel Session: Applications Beyond QCD
Track: Applications Beyond QCD
We calculate the pressure and density equations of state of both unpolarized and polarized non-relativistic fermions at finite temperature in 1D. For attractive contact interactions, where there is no sign problem, we perform a third-order lattice perturbation theory calculation, assess its convergence properties by comparing with hybrid Monte Carlo, and demonstrate agreement with real Langevin. F ... More
Presented by Mr. Andrew LOHEAC on 22 Jun 2017 at 16:20
Type: Parallel Session: Algorithms and Machines
Track: Algorithms and Machines
The LLR method is a novel algorithm that allows the evaluation of the density of states in lattice gauge theory. In this talk I will present our study of the ergodicity properties of the LLR algorithm for the model of Yang Mills SU(3). I will focus on the use of the replica exchange method as tool to alleviate the topological freeze-out of the algorithm.
Presented by Dr. Antonio RAGO on 20 Jun 2017 at 15:20
Type: Parallel Session: Standard Model Parameters and Renormalization
Track: Standard Model Parameters and Renormalization
We investigate the approach of pure SU(2) lattice gauge theory with the Wilson action to its continuum limit using the deconfining transition, the gradient flow, and the cooling flow to set the scale. Of those, the cooling flow turns out to be computationally most efficient. We explore systematic errors due to use of three different energy observables and two distinct reference values for the flow ... More
Presented by Mr. David CLARKE on 21 Jun 2017 at 10:40
Type: Parallel Session: Hadron Structure
Track: Hadron Structure
The well-known discrepancy in the muon $g-2$ between experiment and theory demands further theory investigations in view of the upcoming new experiments. One of the leading uncertainties lies in the hadronic light-by-light scattering contribution (hlbl), that we address with our position-space approach. In this talk we will focus on exploratory studies of a fermion loop without gluon ex ... More
Presented by Mr. Nils ASMUSSEN on 23 Jun 2017 at 17:50
Type: Parallel Session: Hadron Structure
Track: Hadron Structure
We present the first attempt to apply lattice OPE with a fictitious heavy quark to calculate higher moments of the pion light-cone wavefunction. In this talk, we first discuss briefly the approach which was introduced in hep-lat/0507007. Then we discuss the relevant correlators and strategy to extract the moments. Finally, we present preliminary numerical results.
Presented by Dr. santanu MONDAL on 23 Jun 2017 at 15:40
Type: Parallel Session: Theoretical Developments
Track: Theoretical Developments
Flavor-twisted boundary conditions can be used for exponential reduction of finite volume artifacts in flavor-averaged observables in lattice QCD calculations with SU(Nf) light quark flavor symmetry. Finite volume artifact reduction arises from destructive interference effects in a manner closely related to the phase averaging which leads to large Nc volume independence. With a particular choice o ... More
Presented by Mr. Aleksey CHERMAN on 22 Jun 2017 at 15:00
Type: Poster Session: Poster Session
We report on continued studies of the non-perturbative beta function in SU(3) gauge theory with 12 fundamental massless flavors, a model which remains controversial as to the existence of an infrared fixed point. We extend our previous work (Phys. Rev. D94 (2016) no.9, 091501) to stronger gauge couplings and test conformality for this model.
Presented by Prof. Zoltan FODOR on 20 Jun 2017 at 20:30
Type: Parallel Session: Theoretical Developments
Track: Theoretical Developments
The three-particle quantization condition is derived, using the particle-dimer picture in the non-relativistic effective field theory. The procedure for the extraction of various observables in the three-particle sector (the particle-dimer scattering amplitudes, breakup amplitudes, etc.) from the finite-volume lattice spectrum is discussed in detail. As an illustration of the general formalism, th ... More
Presented by Dr. Akaki RUSETSKY on 22 Jun 2017 at 16:00
Type: Parallel Session: Hadron Structure
Track: Hadron Structure
We determine the pion distribution amplitude from three-point functions, where two currents are at the same time with a space-like separation. Having control over the discretization effects turned out to be mandatory. This can be achieved by the choice of suitable channels and by taking into account discretization effects to leading order in the strong coupling. Furthermore, it is necessary to hav ... More
Presented by Mr. Philipp WEIN on 20 Jun 2017 at 18:10
Type: Parallel Session: Applications Beyond QCD
Track: Applications Beyond QCD
We show how lattice Quantum Monte Carlo simulations can be used to calculate electronic properties of carbon nanotubes in the presence of strong electron-electron correlations. We employ the path-integral formalism and use methods developed within the lattice QCD community for our numerical work. We compare our results to empirical data of the Mott gap in large diameter tubes.
Presented by Prof. Thomas LUU on 23 Jun 2017 at 16:00
Type: Poster Session: Poster Session
Track: Algorithms and Machines
In lattice QCD simulations the formulation of the theory in lattice should be chiral in order that symmetry breaking happens dynamically from interactions. In order to guarantee this symmetry on the lattice one uses overlap and domain wall fermions. On the other hand high computational cost of lattice QCD simulations with overlap or domain wall fermions remains a major obstacle of research in the ... More
Presented by Dr. Rudina OSMANAJ (ZEQIRLLARI) on 20 Jun 2017 at 19:30
Type: Parallel Session: Algorithms and Machines
Track: Algorithms and Machines
Using the t-V model, we show how the fermion bag idea can be applied to develop algorithms to Hamiltonian lattice field theories. We argue that fermion world lines suggest an alternative method to the traditional SVD techniques for calculating ratios of determinants in a stable manner. We show the power behind these ideas by extracting the physics of the t-V model on large lattices.
Presented by Ms. Emilie HUFFMAN on 20 Jun 2017 at 17:50
Type: Parallel Session: Standard Model Parameters and Renormalization
Track: Standard Model Parameters and Renormalization
It has been shown that the choice of renormalization scheme is crucial for four-quark operators, in particular for neutral kaon mixing beyond the standard model. In the context of SMOM schemes the choice of projector is not unique, it is part of the definition of the renormalisation scheme. I will present the non-diagonal Fierz relations which relate some projectors which differ by their Dira ... More
Presented by Mr. Garron NICOLAS on 21 Jun 2017 at 13:10
Type: Parallel Session: Algorithms and Machines
Track: Algorithms and Machines
We perform Monte Carlo simulations of the CP$^{N-1}$ model on the square lattice for $N=10$, $21$, and $41$. Our focus is on the severe slowing down related to instantons. To fight this problem we employ open boundary conditions as proposed by Lüscher and Schaefer for lattice QCD. Furthermore we test the efficiency of parallel tempering of a line defect. Our results for open boundary condit ... More
Presented by Dr. Martin HASENBUSCH on 20 Jun 2017 at 15:00
Type: Parallel Session: Software Development
Track: Software Development
This presentation will provide overviews into different technologies. We will review selected technologies that are currently at the disposal of researchers to handle their data. This will include - Filesystems (such as LUSTRE) and strategies to overcome their bottlenecks - Object storages (such as CEPH) and their differneces to filesystems - Management of data on the larger scale, i.e. bet ... More
Presented by Dr. Marcus HARDT on 22 Jun 2017 at 15:40
Type: Parallel Session: Hadron Structure
Track: Hadron Structure
We present a new approach to extracting continuum quasi distributions from lattice QCD. Quasi distributions are defined by matrix elements of a Wilson-line operator extended in a spatial direction, evaluated between nucleon states at finite momentum. We propose smearing this extended operator with the gradient flow to render the corresponding matrix elements finite in the continuum limit. This pro ... More
Presented by Dr. Christopher MONAHAN on 20 Jun 2017 at 15:20
Type: Parallel Session: Nonzero Temperature and Density
Track: Nonzero Temperature and Density
We report on the lattice computation of the Landau gauge gluon propagator at finite temperature, including the non-zero Matsubara frequencies. Furthermore, the Källén-Lehmann representation is inverted and the corresponding spectral density evaluated using a Tikhonov regularisation together with the Morozov discrepancy principle. Implications for gluon confinement are also discussed.
Presented by Dr. Paulo SILVA on 22 Jun 2017 at 15:20
Type: Parallel Session: Hadron Structure
Track: Hadron Structure
In our previous work, the connected and leading disconnected hadronic light-by-light contributions to the muon anomalous magnetic moment (g - 2) have been computed using lattice QCD ensembles corresponding to physical pion mass generated by the RBC/UKQCD collaboration. However, the calculation is expected to suffer from a significant finite volume error, which is only power-law suppressed. In this ... More
Presented by Taku IZUBUCHI on 23 Jun 2017 at 17:30
Type: Plenary Session: Plenary Session - III
I will discuss the recent B-physics results which indicate intriguing deviations from the Standards Model expectations. I will focus on several New Physics scenario which are currently being explored. I will then go through several flavor physics observables (not only those involving b-quark!) and argue that they too could provide us with access to New Physics provided the hadronic uncertainties a ... More
Presented by Dr. Damir BECIREVIC on 20 Jun 2017 at 09:30
Type: Parallel Session: Physics Beyond the Standard Model
Track: Physics Beyond the Standard Model
Studying SU(3) gauge theories with increasing number of fermions is relevant both for understanding the strong dynamics of QCD and for constructing strongly interacting extensions of the Standard Model (e.g. UV completions of composite Higgs models). In order to contrast these many-flavors strongly-interacting theories with QCD, we study the flavor-singlet spectrum as an interesting probe. In fa ... More
Presented by Dr. Enrico RINALDI on 20 Jun 2017 at 15:00
Type: Parallel Session: Nonzero Temperature and Density
Track: Nonzero Temperature and Density
When comparing lattice calculation to experimental data from heavy ion collision experiments, the higher order fluctuations of conserved charges are important observables. An efficient way to study these fluctuations is to determine them from simulations at imaginary chemical potential. In this talk we present results up to the eighth order derivative in muB, calculated on a 48^3x12 lattice with s ... More
Presented by Jana GUENTHER on 23 Jun 2017 at 15:20
Type: Parallel Session: Vacuum Structure and Confinement
Track: Vacuum Structure and Confinement
We study the confining flux tube and its scaling towards the continuum limit in Nf=2+1 QCD at the physical point, discretized with stout smearing improved staggered quarks and the tree level Symanzik gauge action. In particular, we discuss the flux tube dependence on a uniform external magnetic field, showing how it displays anisotropies with respect to the magnetic field direction.
Presented by Dr. Francesco NEGRO on 19 Jun 2017 at 17:20
Type: Parallel Session: Applications Beyond QCD
Track: Applications Beyond QCD
We investigate four-Fermi theories on 3-dimensional lattices. These are Gross-Neveu and Thirring models with a varying numbers of flavours $N_f$. These theories are renormalizable in the $1/N_f$-expansion and possess an interacting continuum limit. The Thirring models are closely related to 3-dimensional QED and serve as field-theoretic models for graphene. For sufficiently small $N_f$ they show a ... More
Presented by Prof. Andreas WIPF on 22 Jun 2017 at 15:20
Type: Parallel Session: Applications Beyond QCD
Track: Applications Beyond QCD
The Thirring model is a Four-Fermi-Theory with a current-current interaction and $U(2N_\text{f})$ chiral symmetry. It is closely related to three-dimensional QED and other models used to describe properties of graphene. In addition it serves as a toy model to study chiral symmetry breaking. In the limit of flavour-number $N_\text{f} \to 1/2$ it is connected to the Gross-Neveau model, which shows ... More
Presented by Dr. Björn WELLEGEHAUSEN on 22 Jun 2017 at 15:40
Type: Parallel Session: Physics Beyond the Standard Model
Track: Physics Beyond the Standard Model
In recent years, many numerical investigations of confining Yang Mills gauge theories near the edge of the conformal window have been carried out using lattice techniques. These studies have revealed that the spectrum of hadrons in nearly conformal ("walking") gauge theories differs significantly from the QCD spectrum. In particular, a light singlet scalar appears in the spectrum which is nearly ... More
Presented by Mr. Andrew GASBARRO on 20 Jun 2017 at 15:40
Type: Parallel Session: Theoretical Developments
Track: Theoretical Developments
We argue that it is possible to uniquely define function support that preserves elementary properties of the function domain. This leads, among other things, to rigorous and general definition of the localization property.
Presented by Prof. Ivan HORVATH on 22 Jun 2017 at 18:50
Type: Parallel Session: Theoretical Developments
Track: Theoretical Developments
Using the example of a two dimensional four-fermion lattice field theory, we show that Feynman diagrams can generate a mass gap in a theory with massless fermions that interact via a marginally relevant coupling. We show this by introducing an infrared cutoff that makes the perturbation series for the partition function convergent. One can then use a Monte Carlo approach to sample sufficiently h ... More
Presented by Prof. Shailesh CHANDRASEKHARAN on 23 Jun 2017 at 15:20
Type: Poster Session: Poster Session
In the landscape of approaches toward the simulation of Lattice Models with complex action the Complex Langevin Equation (CLE) appears as a straightforward method with a simple, well defined set up. Its applicability, however, is controlled by certain specific conditions which are not always satisfied, such as holomorphy and limited diffusion in the non-compact directions. We here provide some det ... More
Presented by Dr. Erhard SEILER on 20 Jun 2017 at 19:30
Intel Xeon Phi processors deliver a huge amount of computational power. When used efficiently, they improve application performance and shorten the time-to-solution. Our talk will describe the processor architecture and discuss on how to efficiently use the hardware resources. We will cover different mechanisms to address this efficient usage. Among the mechanisms, we will introduce QPhiX. QPhiX i ... More
Presented by Harald SERVAT on 20 Jun 2017 at 19:10
Type: Parallel Session: Chiral Symmetry
Track: Chiral Symmetry
It is well-known that the continuum Dirac operator and the lattice Dirac operator of staggered fermions do not necessarily share the same global symmetries. For example in three dimensions the continuum Dirac operator satisfies no chiral symmetry while the staggered Dirac operator does. This change of symmetries has a crucial impact on the number and the kind of the lightest pseudo-scalar mesons s ... More
Presented by Dr. Mario KIEBURG on 20 Jun 2017 at 18:10
Type: Parallel Session: Hadron Spectroscopy and Interactions
Track: Hadron Spectroscopy and Interactions
The lowest-lying glueballs are investigated from $N_f=2$ QCD study on aniostropic lattices. Utilizing the gluonic operators built from Wilson loops to calculate the corresponding correlation functions, we obtain that in the tensor channel, the ground state mass to be $2.367(35)$ GeV and $2.380(61)$ GeV at $m_\pi∼938$ MeV and $650$ MeV, respectively. In the pseudoscalar channel, when we use the g ... More
Presented by Mr. Wei SUN on 20 Jun 2017 at 17:30
Type: Parallel Session: Nonzero Temperature and Density
Track: Nonzero Temperature and Density
SU(2) is the simplest non-abelian gauge theory with fermions without sign problem. Therefore its study on the lattice is a benchmark for other non-perturbative approaches at finite density. We study the Landau-gauge 2-point and 3-point correlation functions of the gauge sector and the running gauge coupling at finite density, and compare them to the vacuum case. We observed no significant ef ... More
Presented by Ms. Ouraman HAJIZADEH on 21 Jun 2017 at 11:50
Type: Plenary Session: Plenary Session - VI
I will present the results of recent lattice studies of the gluon generalised form factors of both hadrons and light nuclei. The generalised transversity gluon distributions are of particular interest since they are purely gluonic; they do not mix with quark distributions at leading twist. In light nuclei they moreover provide a clean signature of non-nucleonic degrees of freedom. The goal of thes ... More
Presented by Dr. Phiala SHANAHAN on 22 Jun 2017 at 11:45
Type: Parallel Session: Algorithms and Machines
Track: Algorithms and Machines
While Lattice QCD presents itself as a problem with an obvious parallelization over lattice sites, it still needs to face the trend in HPC to use wider processors. In addition, maximizing locality becomes increasingly important as wider processors have led to a scenario where available FLOPS has grown faster than the available memory bandwidth. Block Krylov space solvers, which combine solves for ... More
Presented by Dr. Mathias WAGNER on 20 Jun 2017 at 16:20
Type: Plenary Session: Plenary Session - VIII
We discuss a new approach to solve the sign problem based on deforming the domain of integration in the path integral into complex space, the stationary phase contours ("thimbles") being only one of them. We will discuss conceptual and algorithmic issues in implementing this set of ideas. As an example we will show results of field theories with a fermionic sign problem and/or real time dynamic ... More
Presented by Prof. Paulo BEDAQUE on 23 Jun 2017 at 12:30
Type: Parallel Session: Algorithms and Machines
Track: Algorithms and Machines
I discuss the status and performance of Grid software with emphasis on Fermion solver performance on both single and multiple nodes of common CPU technologies, with Cray Aries, Intel Omnipath and Mellanox Infiniband interconnects. Support includes Domain Wall, Wilson and Staggered Fermions. Prospects for GPU support are discussed.
Presented by Prof. Peter BOYLE
Type: Parallel Session: Software Development
Track: Software Development
I will present the strategies we developed in Grid for the HMC sector, in order to support a variety of behaviours without code replication. I will also discuss the current status of the architecture support in view of the upcoming machines.
Presented by Dr. Guido COSSU on 23 Jun 2017 at 16:00
Type: Parallel Session: Weak Decays and Matrix Elements
Track: Weak Decays and Matrix Elements
We compute semi-leptonic $B_s$ decay form factors using Heavy Quark Effective Theory on the lattice. To obtain good control of the $1/m_b$ expansion, one has to take into account not only the leading static order but also the terms arising at $O(1/m_b)$: kinetic, spin and current insertions. We show results for these terms calculated through the ratio method, using our prior results for the static ... More
Presented by Dr. Mateusz KOREN on 19 Jun 2017 at 15:50
Type: Parallel Session: Weak Decays and Matrix Elements
Track: Weak Decays and Matrix Elements
We present a lattice computation of pseudoscalar and vector heavy-light meson masses for heavy-quark masses ranging from the physical charm mass up to $\simeq 4$ times the physical b-quark mass. We employ the gauge configurations generated by the European Twisted Mass Collaboration (ETMC) with $N_f = 2+1+1$ dynamical quarks at three values of the lattice spacing ($a \simeq 0.062 - 0.089$ fm) with ... More
Presented by Aurora MELIS on 23 Jun 2017 at 18:30
Type: Parallel Session: Hadron Structure
Track: Hadron Structure
We present a lattice calculation of the Hadronic Vacuum Polarization (HVP) contribution of the strange and charm quarks to the anomalous magnetic moment of the muon including leading-order electromagnetic corrections. We employ the gauge configurations generated by the European Twisted Mass Collaboration (ETMC) with $N_f = 2+1+1$ dynamical quarks at three values of the lattice spacing ($a \simeq 0 ... More Presented by Dr. Simula SILVANO on 22 Jun 2017 at 18:30 Type: Parallel Session: Nonzero Temperature and Density Track: Nonzero Temperature and Density We use 4stout improved staggered lattice data at imaginary chemical potentials to calculate virial coefficients in finite temperature QCD. Since the virial expansion is an expansion in the fugacity, i.e. the exponential of the chemical potential, for imaginary chemical potentials the coefficients simply become Fourier coefficients, allowing for an accurate determination from our simulations. We ... More Presented by Attila PASZTOR on 23 Jun 2017 at 18:50 Type: Plenary Session: Plenary Session - X After a brief introduction on ongoing experimental and theoretical activities on$(g-2)_\mu$, I will describe recent progress in approaching the calculation of the hadronic light-by-light contribution with dispersive methods. I will discuss general properties of the four-point function of the electromagnetic current in QCD, its Lorentz decomposition and dispersive representation. Based on these I ... More Presented by Prof. Gilberto COLANGELO on 24 Jun 2017 at 12:00 Type: Parallel Session: Hadron Structure Track: Hadron Structure We present a progress report on the Fermilab Lattice, HPQCD, and MILC Collaborations’ calculation of the hadronic vacuum polarization contribution to the muon anomalous magnetic moment (g-2). This calculation is needed in order to make full use of the upcoming Fermilab and J-PARC experiments to measure the muon g-2 to higher precision and improve the sensitivity to physics beyond the Standard M ... More Presented by Dr. Ruth VAN DE WATER on 22 Jun 2017 at 15:40 Type: Parallel Session: Hadron Spectroscopy and Interactions Track: Hadron Spectroscopy and Interactions We present results of a lattice calculation of heavy-light tetraquark states with charm & bottom quarks in the heavy sector and up & down quarks in light sector while the strange quark appears interchangeably in both sectors. The calculation employs the highly improved staggered quark action (HISQ) as adopted by the MILC collaboration in the sea sector and overlap action in the valence sector. The ... More Presented by Dr. Parikshit JUNNARKAR on 23 Jun 2017 at 18:30 Type: Parallel Session: Physics Beyond the Standard Model Track: Physics Beyond the Standard Model As a first step in the study of$Sp(2N)$composite Higgs models, we obtained a set of novel numerical results for the pure gauge$Sp(4)$lattice theory in$3+1$space-time dimensions. Results for the continuum extrapolations of the string tension and the glueball mass spectrum are presented and their values are compared with the same quantities in neighbouring$SU(N)$models. Presented by Dr. Davide VADACCHINO on 19 Jun 2017 at 17:00 Type: Parallel Session: Physics Beyond the Standard Model Track: Physics Beyond the Standard Model Higgs compositeness, i.e. the framework in which the Higgs boson arises as a Goldstone boson of a novel strong interaction, provides an elegant way to circumvent the hierarchy problem in the standard model. In order to study compositeness, the first step is to understand the global symmetry breaking pattern in the novel strong force, which has to be compatible with the symmetries of the standard m ... More Presented by Prof. Biagio LUCINI on 19 Jun 2017 at 16:40 Type: Parallel Session: Physics Beyond the Standard Model Track: Physics Beyond the Standard Model As part of an ongoing program to study$Sp(2N)$gauge theories as potential realisations of composite Higgs models, we consider the case of$Sp(4)$on the lattice, both as a pure gauge theory, and with two Dirac fermion flavors in the fundamental representation. In order to compare results between these two cases and maintain control of lattice artefacts, we make use of the gradient flow to set th ... More Presented by Dr. Ed BENNETT on 19 Jun 2017 at 17:20 Type: Parallel Session: Physics Beyond the Standard Model Track: Physics Beyond the Standard Model We consider Sp(4) gauge theories with two Dirac fermion flavors in the fundamental representation on a lattice, which provide a concrete example of the microscopic realization of the SO(6)/SO(5) composite Higgs model. For numerical studies we use the standard Wilson lattice action and the Hybrid Monte-Carlo algorithms. By performing a mass scan we first identify the first order bulk transition and ... More Presented by Dr. Jong-Wan LEE on 19 Jun 2017 at 17:40 Type: Parallel Session: Physics Beyond the Standard Model Track: Physics Beyond the Standard Model We present results from two projects on lattice calculations for the Higgs-Yukawa model. First we report progress on the search of first-order thermal phase transitions in the presence of a dimension-six operator, with the choices of bare couplings that lead to viable phenomenological predictions. In this project the simulations are performed using overlap fermions. Secondly, our study for appl ... More Presented by Prof. C.-J. David LIN on 23 Jun 2017 at 15:20 Type: Parallel Session: Hadron Structure Track: Hadron Structure In order to perform high precision calculations in lattice QCD for observables of physical interest, especially for dimensionful quantities, it is important to be able to determine the lattice spacing with high accuracy. One choice for scale setting is the observable$w_0$based on the Wilson flow. It is relatively easy to measure on individual ensembles with high precision. However the value of$ ... More
Presented by Mr. Lukas VARNHORST on 21 Jun 2017 at 11:50
Type: Parallel Session: Theoretical Developments
Track: Theoretical Developments
We investigate the possibility of using numerical stochastic perturbation theory (NSPT) to probe high orders in the perturbative expansion of lattice gauge theories with massless Wilson fermions. Twisted boundary conditions are used to regularise the gauge zero-mode; the extension of these boundary conditions to include fermions in the fundamental representation requires to introduce a smell degre ... More
Presented by Mr. Gianluca FILACI on 22 Jun 2017 at 15:40
Type: Poster Session: Poster Session
In the calculation of quark condensates using staggered fermions, the contribution induced by the zero modes of the Dirac operator behaves as a simple pole as approaching to the chiral limit. We use Lanczos algorithm to find the would-be zero modes of the staggered Dirac operator and identify their quantum numbers by the spectral flow method. We plan to apply this method to the calculation of quar ... More
Presented by Mr. Hwancheol JEONG on 20 Jun 2017 at 19:30
Type: Parallel Session: Standard Model Parameters and Renormalization
Track: Standard Model Parameters and Renormalization
We upload a summary that allows participants to write their proceeding contribution starting from a template tex file.
Presented by Patrick FRITZSCH
Type: Parallel Session: Theoretical Developments
Track: Theoretical Developments
Through the development of many-body methodology and algorithms, it has become possible to describe quantum systems composed of a large number of particles with great accuracy. Essential to all these methods is the application of auxiliary fields via the Hubbard-Stratonovich transformation. This transformation effectively reduces two-body interactions to interactions of one particle with the auxil ... More
Presented by Mr. Christopher KOERBER on 22 Jun 2017 at 16:20
Type: Parallel Session: Standard Model Parameters and Renormalization
Track: Standard Model Parameters and Renormalization
We present results for the strong coupling constant ($alpha_s$) and the charm quark mass ($m_c$) obtained from the moments of pseudoscalar current-current correlators. Our calculation employs the four flavor (2+1+1) HISQ ensembles generated by the MILC collaboration with six lattice spacings, including five with physical light-quark masses. We improve upon earlier calculations by including in our ... More
Presented by Dr. Aarti VEERNALA on 21 Jun 2017 at 10:00
Type: Parallel Session: Nonzero Temperature and Density
Track: Nonzero Temperature and Density
The sign problem in particle physics appears in QCD as soon as a non-zero chemical potential is introduced. This prevents direct lattice simulations to determine the phase structure of the strongly interacting matter. Complex Langevin methods have been successfully used for various models or approximations of QCD, however, in some scenarios it converges to incorrect results. We will present a new ... More
Presented by Dr. Benjamin JAEGER on 20 Jun 2017 at 18:50
Type: Parallel Session: Software Development
Track: Software Development
Quantities in lattice QCD are estimated from statistical fits to lattice correlation functions. For example, a meson mass may be estimated from a fit to a two-point function, $C(t)$, computed at $p$ timeslices, where each measurement is averaged over a sample of $n$, statistically independent gauge configurations. Correlations among $C(t)$ at nearby time slices means that the statistical pr ... More
Presented by Dr. james SIMONE on 22 Jun 2017 at 18:30
Type: Parallel Session: Nonzero Temperature and Density
Track: Nonzero Temperature and Density
The computation of real-time properties, such as transport coefficients or bound state spectra of strongly interacting quantum fields in thermal equilibrium is a pressing matter. Since the sign problem prevents a direct evaluation of these quantities, lattice data needs to be analytically continued from the Euclidean domain of the simulation to Minkowski time, in general an ill-posed inverse probl ... More
Presented by Dr. Alexander ROTHKOPF on 19 Jun 2017 at 17:40
Type: Parallel Session: Physics Beyond the Standard Model
Track: Physics Beyond the Standard Model
This talk summarizes the results of the DESY-Münster collaboration for N=1 supersymmetric Yang-Mills theory with the gauge group SU(3). It is an updated status report with respect to our preliminary data presented at the last conference. In order to control the lattice artefacts we have now considered a clover improved fermion action and different values of the gauge coupling.
Presented by Dr. Georg BERGNER on 22 Jun 2017 at 15:00
Type: Poster Session: Poster Session
It is necessary to improve flavor-changing currents for calculating $\bar{B}\rightarrow D^{(*)}\ell\bar{\nu}$ semi-leptonic form factors using Oktay-Kronfeld (OK) heavy-quarks. The OK action reduces the heavy-quark discretization effect up to $\mathcal{O}(\lambda^3)$ in the HQET power counting. To get a full advantage of the OK action, we need to improve the currents up to the same level as well. ... More
Presented by Mr. JAEHOON LEEM on 20 Jun 2017 at 19:30
Type: Parallel Session: Weak Decays and Matrix Elements
Track: Weak Decays and Matrix Elements
We present lattice QCD results for the matrix elements of $R_2$ and other dimension-7, $\Delta B = 2$ operators relevant for calculations of $\Delta \Gamma_s$, the $B_s-\bar{B}_s$ width difference. We have computed correlation functions using 5 ensembles of the MILC Collaboration's $2+1+1$-flavor gauge field configurations, spanning 3 lattice spacings and light sea quarks masses down to the ... More
Presented by Dr. Matthew WINGATE on 20 Jun 2017 at 16:00
Type: Parallel Session: Weak Decays and Matrix Elements
Track: Weak Decays and Matrix Elements
Because of the small size of the ratio $A_2/A_0$ of the $I=2$ to $I=0$ $K\to\pi\pi$ decay amplitudes (the $\Delta I=1/2$ rule) the effects of electromagnetism on $A_2$ may be a factor of 20 larger than given by a naive $O(\alpha)$ estimate. Thus, if future calculations of $A_2$ and $\varepsilon'/\varepsilon$ are to achieve 10% accuracy, these effects need to be included. Here we present the firs ... More
Presented by Prof. Norman CHRIST on 21 Jun 2017 at 12:10
Type: Parallel Session: Weak Decays and Matrix Elements
Track: Weak Decays and Matrix Elements
First-principle lattice calculation of inclusive B meson semileptonic decays is possible for a certain class of moments that is connected to the structure function at unphysical kinematics by analytic continuation. We present an exploratory lattice calculation and a comparison with the heavy quark expansion technique.
Presented by Dr. Shoji HASHIMOTO on 21 Jun 2017 at 10:20
Type: Parallel Session: Vacuum Structure and Confinement
Track: Vacuum Structure and Confinement
I will present some recent results obtained in the study of the color magnetic and electric screening masses in the QCD plasma. In particular, I will focus on how the masses get modified by strong external fields which are expected to be created in physical situations such as heavy-ion collisions.
Presented by Mr. Andrea RUCCI on 20 Jun 2017 at 15:00
Type: Parallel Session: Vacuum Structure and Confinement
Track: Vacuum Structure and Confinement
We report on an instanton-based analysis of gluon Green functions in the Landau gauge for low momenta; in particular we used lattice results for $\alpha_s$ in the symmetric momentum subtraction scheme (${\rm MOM}$) for large-volume lattice simulations. We have exploited quenched gauge field configurations, $N_f=0$, with both Wilson and tree-level Symanzik improved actions, and unquenched ones wit ... More
Presented by Dr. Feliciano DE SOTO on 19 Jun 2017 at 15:30
Type: Parallel Session: Vacuum Structure and Confinement
Track: Vacuum Structure and Confinement
In order to better understand the role played by instantons behind nonperturbative dynamics, we investigate the instanton contributions to the gluonic two point correlation functions in the SU(2) YM theory. Pseudoscalar-pseudoscalar and pseudoscalar-scalar gluonic correlation functions are calculated on the lattice at various temperatures and compared with the instanton calculus. We discuss how t ... More
Presented by Mr. Shingo MORI on 19 Jun 2017 at 14:50
Type: Parallel Session: Vacuum Structure and Confinement
Track: Vacuum Structure and Confinement
Paradigm shift in gauge topology at finite temperatures, from the instantons to their constituents -- instanton-dyons -- has recently lead to studies of their ensembles and very significant advances. Like instantons, they have fermionic zero modes, and their collectivization at sufficiently high density explains the chiral symmetry breaking. Unlike instantons, these objects have electric ... More
Presented by Prof. Edward SHURYAK on 19 Jun 2017 at 14:30
Type: Parallel Session: Physics Beyond the Standard Model
Track: Physics Beyond the Standard Model
Mass-split systems based on a conformal infrared fixed point provide a low-energy effective description of BSM systems with large scale separation. We report results of exploratory investigations with four light and eight heavy flavors using staggered fermions, and up to five different values for the light flavor mass, five different heavy flavor masses, and two values of the bare gauge coupling ... More
Presented by Prof. Claudio REBBI on 20 Jun 2017 at 18:50
Type: Plenary Session: Plenary Session - V
In our recent study of 2-flavor lattice QCD using chiral fermions, we find strong suppression of axial U(1) anomaly above the critical temperature of chiral phase transition. Our simulation data also indicate suppression of topological susceptibility compared to that predicted by the dilute instanton gas approximation (DIGA). In this talk, we present both of our theoretical and numerical evidence ... More
Presented by Dr. Hidenori FUKAYA on 22 Jun 2017 at 09:50
Type: Parallel Session: Hadron Structure
Track: Hadron Structure
We present results for the QED and strong isospin breaking corrections to the hadronic vacuum polarization using $N_f=2+1$ Domain Wall fermions. QED is included in an electro-quenched setup using two different methods, a stochastic and a perturbative approach. Results and statistical errors from both methods are directly compared with each other.
Presented by Dr. Vera GUELPERS on 22 Jun 2017 at 17:30
Type: Parallel Session: Hadron Structure
Track: Hadron Structure
Modern advances in experimental techniques now make it possible to test the weak interaction in nucleon/nuclear systems. In order to reliably interpret such measurements as tests of the standard model, it is often a necessity to make the assumption of good charge symmetry underlying the hadronic/nuclear interactions. Recent lattice QCD simulations have started to constrain the charge symmetry brea ... More
Presented by Dr. James ZANOTTI on 19 Jun 2017 at 17:20
Type: Parallel Session: Hadron Spectroscopy and Interactions
Track: Hadron Spectroscopy and Interactions
We compute the mass splittings between pseudoscalar mesons using Nf=2+1+1 staggered lattice configurations at pion and kaon masses around their respective physical values. We include the u-d mass difference and QED effects in the valence sector.
Presented by Dr. Balint TOTH on 21 Jun 2017 at 10:40
Type: Parallel Session: Hadron Structure
Track: Hadron Structure
We present results for the isovector and isoscalar charges of the nucleon. The 2+1+1-flavor calculations were done using MILC HISQ ensembles with three lattice spacings a=0.12, 0.09, 0.06 fm and three pion masses approximately 310, 220, 130 MeV. The 2+1-flavor clover calculations were done on four ensembles with approximately 300 and 190 MeV pion masses.
Presented by Dr. Rajan GUPTA on 19 Jun 2017 at 14:30
Type: Parallel Session: Software Development
Track: Software Development
High Performance Computing is often performed on scarce, shared computing resources. To ensure computers are used to their full capacity, administrators often incentivize large workloads that are not possible on smaller systems. Measurements in Lattice QCD frequently do not scale to machine-size workloads. By bundling tasks together we can create large jobs suitable for gigantic partitions. ... More
Presented by Dr. Evan BERKOWITZ on 22 Jun 2017 at 16:20
Type: Parallel Session: Theoretical Developments
Track: Theoretical Developments
We derive a full Kramers-Wannier dualization of the SU(2) principal chiral model. In a first step the trace and color multiplications in the action are written explicitly, such that only commuting numbers ("Abelian Color Fluxes") remain. The individual Boltzmann factors are then expanded and the original degrees of freedom are integrated out explicitly. The expansion indices become the new variabl ... More
Presented by Prof. Christof GATTRINGER on 21 Jun 2017 at 12:10
Type: Parallel Session: Nonzero Temperature and Density
Track: Nonzero Temperature and Density
I will discuss the issue of Landau levels of quarks in lattice QCD in an external magnetic field. I will show that in the two-dimensional case the lowest Landau level can be identified unambiguously even if the strong interactions are turned on. Starting from this observation, I will then show how one can define a "lowest Landau level" in the four-dimensional case, and discuss how much of the obse ... More
Presented by Dr. Matteo GIORDANO on 19 Jun 2017 at 15:10
Type: Parallel Session: Theoretical Developments
Track: Theoretical Developments
Through a careful study of smooth Wilson loop operators on the lattice, we are able to obtain very accurate confirmation of the $1/N^2$ scaling predicted by t Hooft for the pure $\mathrm{SU}(N)$ gauge theory. We present our results for Wilson loops smoothed with the Yang-Mills gradient flow and matched through the scale $t_0$. This allows us to have renormalizable operators and test the $1/N^2$ ... More
Presented by Mr. Miguel Francisco GARCÍA VERA on 23 Jun 2017 at 15:00
Type: Parallel Session: Software Development
Track: Software Development
In October, 2016, the US Department of Energy launched an Exascale Computation Project that aims to deploy exascale computing resources for science and engineering in the early 2020's. The project brings together application teams, software developers, and hardware vendors in realizing this goal. Lattice QCD is one of the applications. Members of the US lattice gauge theory community with signi ... More
Presented by Carleton DETAR on 22 Jun 2017 at 15:00
Type: Plenary Session: Plenary Session - IX
Lattice QCD has begun exploring properties of light nuclear systems beyond their simplest properties such as their lowest-lying spectra. While the progress has been made in the past year in pursuing the physical quark-mass calculations with reasonable precision, technologies have been developed, and results have been obtained, for simplest nuclear matrix elements and nuclear reactions at heavier q ... More
Presented by Dr. Zohreh DAVOUDI on 24 Jun 2017 at 09:30
Presented by Dr. Antonio RAGO on 24 Jun 2017 at 09:00
Type: Parallel Session: Hadron Structure
Track: Hadron Structure
We present lattice QCD results by the BMW collaboration for the leading-order contribution of the hadron vacuum polarization (LO-HVP) to anomalous magnetic moments of all charged leptons. Calculations are performed with u, d, s and c quarks at their physical masses, in volumes of linear extent larger than 6 fm, and at six values of the lattice spacing, allowing for controlled continuum extrapolati ... More
Presented by Dr. Kohtaroh MIURA on 22 Jun 2017 at 15:20
Type: Parallel Session: Hadron Spectroscopy and Interactions
Track: Hadron Spectroscopy and Interactions
We investigate baryon-baryon (BB) interactions via the time-dependent HAL QCD method which enables us to derive potentials from Nambu-Bethe-Salpeter (NBS) wave function simulated on the lattice. The simulations are performed with (almost) physical quark masses ($m_\pi=146$ MeV) and a huge lattice volume of La = $8.1$fm. We report the latest results of BB potentials and their scattering o ... More
Presented by Dr. Kenji SASAKI on 22 Jun 2017 at 16:00
Type: Parallel Session: Hadron Spectroscopy and Interactions
Track: Hadron Spectroscopy and Interactions
We used Borici-Creutz fermion to study discrete chiral symmetry breaking at strong coupling in 2-dim Gross-Neveu model and mass spectra in 2-dim field theories. Mixed action lattice QCD study with Borici-Creutz valence quarks on staggered sea quarks is carried out. The counter terms are fixed nonperturbatively to restore the broken symmetries. The effects of partial quenching and unitarity violat ... More
Presented by Dr. Subhasish BASAK on 21 Jun 2017 at 09:00
Type: Parallel Session: Physics Beyond the Standard Model
Track: Physics Beyond the Standard Model
We present results from a study of Euclidean dynamical triangulations in an attempt to make contact with Weinberg's asymptotic safety scenario for quantum gravity. We find that a fine-tuning is necessary in order to recover semiclassical behavior, and that once this tuning is performed, our simulations provide evidence in support of the asymptotic safety scenario for gravity. We discuss our motiv ... More
Presented by John LAIHO on 23 Jun 2017 at 16:00
Type: Parallel Session: Nonzero Temperature and Density
Track: Nonzero Temperature and Density
The canonical approach is a powerful tool to circumvent sign problem in LQCD. Although it has its own difficulties it provides opportunity to determine QCD phase transition line. Using improved Wilson fermions we calculated number density at nonzero imaginary chemical potential for confinement and deconfinement phases, restored canonical partition functions Zn and did extrapolation into the real ... More
Presented by Mr. Denis BOYDA on 23 Jun 2017 at 17:50
Type: Poster Session: Poster Session
We compute the hadronic tensor $W_{\mu\nu}$ in the Euclidean space by calculating 4-point correlation functions on the lattice, two topologically distinct connected insertons are considered which help to separate the connected sea parton contribution from that of the disconnected sea. We try to convert the Euclidean hadronic tensor to Minkowski space through inverse Laplace transform. As an explor ... More
Presented by Prof. Liu KEH-FEI on 20 Jun 2017 at 20:30
Type: Parallel Session: Theoretical Developments
Track: Theoretical Developments
While the sign problem of the Dirac fermion is conditioned by the positivity of a determinant, that of the Majorana fermion is conditioned by the positivity of a Pfaffian. We introduce one sufficient condition for the positivity of a Pfaffian. Based on the positivity condition, we study an effective model of the Majorana edge states in condensed matter physics. We also present the application t ... More
Presented by Arata YAMAMOTO on 21 Jun 2017 at 09:00
Type: Parallel Session: Physics Beyond the Standard Model
Track: Physics Beyond the Standard Model
The detection of gravitational waves (GWs) has raised interest in cosmology and particle physics as they can reveal unique information about the early universe, and new experiments to detect them, like LISA and DECIGO, will take place in the future. In the meantime numerical simulations are needed to compute the spectrum and strength of the gravitational wave signal from various scenarios. In this ... More
Presented by Sara TÄHTINEN on 22 Jun 2017 at 18:30
Type: Poster Session: Poster Session
The nature of resonances and excited states near decay thresholds is encoded in phase shifts, which can be extracted from single-particle and multiparticle correlators in finite volumes. Lattice calculations have only recently reached the required precision for a reliable study of such correlators. The distillation method has been a significative improvement insofar as it simplifies quark contract ... More
Presented by Mr. Simon WEISHÄUPL on 20 Jun 2017 at 19:30
Type: Parallel Session: Vacuum Structure and Confinement
Track: Vacuum Structure and Confinement
In this talk, we study the double-winding Wilson loops in the SU(N) Yang-Mills theory on the lattice. We discuss how the area law falloff of the double-winding Wilson loop average is modified by changing the enclosing contours $C_1$ and $C_2$ for various values of the number of color $N$. By using the strong coupling expansion, we evaluate the double-winding Wilson loop average in the lattice ... More
Presented by Akihiro SHIBATA on 20 Jun 2017 at 15:40
Type: Parallel Session: Applications Beyond QCD
Track: Applications Beyond QCD
We present first-principle lattice study of continuity conjecture in $2d$ $SU(N) \times SU(N)$ Principal Chiral Model (PCM) on $R \times S^1$ with respect to circumference $L$ of $S^1$ in the presence of $Z(N)$-preserving twist. The twist can be considered as analogous to Twisted Eguchi-Kawai reduction in lattice gauge theory. We study static correlation length and find that it exhibits a peak at ... More
Presented by Mr. Semen VALGUSHEV on 23 Jun 2017 at 18:10
Type: Parallel Session: Hadron Structure
Track: Hadron Structure
We report our study of finite volume effect in the leading hadronic contribution to muon g-2 on gauge ensembles with Nf=2+1 dynamical clover fermions generated by PACS collaboration . We compare connected HVP with different physical volumes, from 5.4 -- 8 fm^4, in a fixed lattice spacing a^-1=2.33 GeV in physical pion, We also estimate an extrapolated value into the infinite volume limit and discu ... More
Presented by Dr. Eigo SHINTANI on 22 Jun 2017 at 17:10
Type: Parallel Session: Hadron Structure
Track: Hadron Structure
We present a study of the isospin-breaking corrections to pseudoscalar meson masses using the gauge configurations produced by the ETM Collaboration with $N_f=2+1+1$ dynamical quarks at three lattice spacings varying from 0.089 to 0.062 fm. Our method is based on a combined expansion of the path integral in powers of the small parameters $(m_d - m_u)/\Lambda_{QCD}$ and $\alpha_{em}$, where $m_f$ i ... More
Presented by DAVIDE GIUSTI on 22 Jun 2017 at 18:50
Type: Parallel Session: Nonzero Temperature and Density
Track: Nonzero Temperature and Density
Lefschetz-thimble method becomes a powerful tool to study the sign problem. It defines the steepest descent contours by the gradient flow in complexified field configurations. Solutions of the gradient flow, however, generically blow up in a finite time, and thus it must be solved with great cares. We propose a new gradient flow without blow-ups that equally solves the sign problem as the conv ... More
Presented by Dr. Yuya TANIZAKI on 21 Jun 2017 at 09:40
Type: Parallel Session: Weak Decays and Matrix Elements
Track: Weak Decays and Matrix Elements
We report on the status of an ongoing effort by the RQCD and ALPHA Collaborations, aimed at determining leptonic decay constants of charmed mesons. Our analysis is based on large-volume ensembles generated within the CLS effort, employing $N_f=2+1$ non-perturbatively $\mathcal{O}(a)$ improved Wilson quarks, tree-level Symanzik-improved gauge action and open boundary conditions. The ensembles ... More
Presented by Mr. Kevin ECKERT on 21 Jun 2017 at 09:20
Type: Parallel Session: Hadron Spectroscopy and Interactions
Track: Hadron Spectroscopy and Interactions
Lattice QCD simulations of multi-baryon correlation functions can determine structure and reactions of nuclei without encountering the baryon chemical potential sign problem. However, they suffer from a signal-to-noise problem where Monte Carlo estimates of observables have quantum fluctuations that are exponentially larger than their average values. Recent lattice QCD results demonstrate that th ... More
Presented by Michael WAGMAN on 22 Jun 2017 at 17:10
Type: Parallel Session: Hadron Structure
Track: Hadron Structure
Measurements and theoretical calculations of meson form factors are essential for our understanding of internal hadron structure and QCD, the dynamics that bind the quarks in hadrons. The pion form factor has been measured at small momentum transfer (Q^2) by scattering from atomic electrons and from scattering of electrons from the pion cloud around a proton. On the other hand, in the limit of ver ... More
Presented by Dr. Jonna KOPONEN on 23 Jun 2017 at 15:20
Type: Parallel Session: Nonzero Temperature and Density
Track: Nonzero Temperature and Density
We study the phase diagram of QCD at finite isospin density using two flavors of staggered quarks. We investigate the low temperature region of the phase diagram where we find a pion condensation phase at high chemical potential. We started a basic analysis of the spectrum at finite isospin density. In particular, we measured pion masses inside and outside of the pion condensation phase. In agre ... More
Presented by Dr. Philipp SCIOR on 20 Jun 2017 at 16:00
Type: Parallel Session: Hadron Structure
Track: Hadron Structure
We present our preliminary results on the calculation of hadronic light-by-light forward scattering amplitudes using vector four-point correlation functions computed on the lattice. Using a dispersive approach, these forward scattering amplitudes can be described by $\gamma^* \gamma^* \to$ hadrons fusion cross sections and then compared with phenomenology. We show that only a few states are needed ... More
Presented by Dr. Antoine GERARDIN on 23 Jun 2017 at 18:10
Type: Parallel Session: Theoretical Developments
Track: Theoretical Developments
Many correlators in lattice QCD show an exponential degradation of the signal-to-noise ratio with distance. This problem can be addressed by performing *multilevel* Monte Carlo sampling. However, to date, multilevel techniques have been limited to bosonic theories. To overcome this limitation, we developed a factorization into independent spacetime domains of the Wilson fermions determinant con ... More
Presented by Dr. Marco CÈ on 22 Jun 2017 at 15:20
Type: Plenary Session: Plenary Session - VII
Models for what may lie behind the Standard Model often require non-perturbative calculations in strongly coupled field theory. This creates opportunities for lattice methods, to obtain quantities of phenomenological interest as well as to address fundamental dynamical questions. I will survey recent work in this area.
Presented by Prof. Benjamin SVETITSKY on 23 Jun 2017 at 09:30
Type: Parallel Session: Theoretical Developments
Track: Theoretical Developments
In principle the loop equation provides a complete formulation of a gauge theory purely in terms of Wilson loops. In the case of lattice gauge theories the loop equation is a well defined equation for a discrete set of quantities and can be easily solved at strong coupling either numerically or by series expansion. At weak coupling, however, we argue that the equations are not well defined unless ... More
Presented by Prof. Martin KRUCZENSKI on 21 Jun 2017 at 09:40
Type: Parallel Session: Theoretical Developments
Track: Theoretical Developments
We analyze the CP(1) model using the Loop optimization for Tensor network renormalization (Loop-TNR). This method makes it possible to completely remove short-range entanglement at each coarse-graining step which can not be removed by the Tensor renormalization group. We compare the results of these methods in the presence of the theta term.
Presented by Mr. Hikaru KAWAUCHI on 23 Jun 2017 at 17:30
Type: Parallel Session: Algorithms and Machines
Track: Algorithms and Machines
With recent developments in parallel supercomputing architecture, many core, multi-core, and GPU processors are now commonplace resulting in more levels of parallelism, memory hierarchy, and programming complexity. It has been necessary to adapt the MILC code to these new processors starting with NVIDIA GPUs and more recently the Intel Xeon Phi processors. We report on our efforts to port and opti ... More
Presented by Dr. Ruizi LI on 20 Jun 2017 at 17:10
Type: Parallel Session: Hadron Structure
Track: Hadron Structure
We have calculated the magnetic moments of vector ro and K* mesons in lattice gauge theory for various masses of the light and strange quarks. The dependence of the g-factor on the pion mass was explored. The extrapolation to the phisical pion mass has been carried out.
Presented by Dr. Luschevskaya ELENA on 21 Jun 2017 at 10:20
Type: Parallel Session: Hadron Spectroscopy and Interactions
Track: Hadron Spectroscopy and Interactions
We perform hybrid Monte Carlo simulation of lattice QCD with $N_f=2+1+1$ optimal domain-wall quarks on the $32^3 \times 64$ lattice with lattice spacing $a \sim 0.06$~fm, and generate 3 gauge ensembles with pion masses 280-400 MeV. We compute the point-to-point quark propagators, and measure the time-correlation functions of meson and baryon interpolators. The mass spectra of the lowest-lyi ... More
Presented by Prof. Ting-Wai CHIU on 21 Jun 2017 at 09:20
Type: Parallel Session: Theoretical Developments
Track: Theoretical Developments
The problem of finding a positive distribution, which corresponds to a given complex density in complex Langevin approach, is studied. By the requirement that the moments of the positive distribution and of the complex density are equal, one can reduce the problem to solving the matching conditions. After imposing the positivity of the distribution, these conditions become a set of quadratic equat ... More
Presented by Mr. Adam WYRZYKOWSKI on 22 Jun 2017 at 18:30
Type: Parallel Session: Nonzero Temperature and Density
Track: Nonzero Temperature and Density
We analyse the behaviour of hyperons with strangeness $S=-1,-2$ in the hadronic and quark gluon plasma phases, with particular interest in parity doubling and its emergence as the temperature grows. This study uses our FASTSUM anisotropic $N_f = 2 + 1$ ensembles, with four temperatures below and four above the deconfinement transition temperature, $T_c$. The positive-parity groundstate masses ... More
Presented by Davide DE BONI on 20 Jun 2017 at 16:20
Type: Parallel Session: Chiral Symmetry
Track: Chiral Symmetry
Chiral symmetry breaking in massless QCD is a very important feature in the current understanding of low energy physics. Low - lying Dirac modes are suitable to help us understand the spontaneous chiral symmetry breaking, since the formation of a non zero chiral condensate is an effect of their accumulation near zero. The Banks – Casher relation links the spectral density of the Dirac operator ... More
Presented by Dr. Rudina OSMANAJ (ZEQIRLLARI) on 20 Jun 2017 at 17:30
Type: Parallel Session: Software Development
Track: Software Development
We present a case study for data analysis in lattice gauge theory. Three features are key to our framework: relational databases for storage of high-level lattice results, fast open-source software for analysis, and a dashboard environment based on the Jupyter notebook. We talk about our recent experiences learning, using, and combining these tools. Finally, we advocate their wider usage in the la ... More
Presented by Mr. William JAY on 23 Jun 2017 at 18:10
Type: Parallel Session: Hadron Spectroscopy and Interactions
Track: Hadron Spectroscopy and Interactions
We report on our progress with the ongoing study of exotic, heavy tetraquark states, $qq’ \bar Q\bar Q’$. With regards to the previously reported $\bar Q\bar Q’=\bar b\bar b$ case, we have significantly increased our statistics by computing and saving more propagators on publicly available dynamical $n_f =2+1$ Wilson-Clover gauge configurations, generated by the PACS-CS collaboration, with ... More
Presented by Dr. Anthony FRANCIS on 23 Jun 2017 at 17:50
Type: Plenary Session: Plenary Session - II
I will review a recent proposal for factorizing the fermion determinant in lattice QCD that leads to a local bosonic action in the block fields. Once combined with the factorization of the propagator, it paves the way for multilevel Monte Carlo integration in the presence of fermions opening new perspectives in lattice QCD.
Presented by Leonardo GIUSTI on 19 Jun 2017 at 12:00
Type: Poster Session: Poster Session
I present a multi-grid Lanczos algorithm that reduces the memory requirements both on disk and in working memory by one order of magnitude for RBC/UKQCD's 48I and 64I ensembles at the physical pion mass. The precision of the resulting eigenvectors is on par with exact deflation.
Presented by Christoph LEHNER on 20 Jun 2017 at 20:30
Type: Parallel Session: Hadron Spectroscopy and Interactions
Track: Hadron Spectroscopy and Interactions
We demonstrate the efficacy of the stochastic LapH method to treat all-to-all quark propagation on a $N_\mathrm{f} = 2+1$ CLS ensemble with large linear spatial extent $L = 5.5 \, \mathrm{fm}$ and $m_\pi L = 6.2$. Employing interlace-16 dilution in Laplacian eigenvector space, we obtain the benchmark elastic isovector $p$-wave pion-pion scattering amplitude to good precision already on a relativel ... More
Presented by Ben HÖRZ on 19 Jun 2017 at 14:30
Type: Plenary Session: Plenary Session - IV
It is shown that baryon chiral perturbation theory can be employed to calculate the excited-state contamination in various nucleon observables due to two-particle nucleon-pion states. Leading order results are presented for the nucleon axial, tensor and scalar charge and three Mellin moments of parton distribution functions (quark momentum fraction, helicity and transversity moment). Taking into ... More
Presented by Dr. Oliver BAER on 20 Jun 2017 at 11:45
Type: Parallel Session: Algorithms and Machines
Track: Algorithms and Machines
Simulations at physical quark masses are affected by the critical slowing down of the solvers.Multigrid preconditioning has proved to effectively deal with this problem. The ETM collaboration is performing multigrid accelerated simulations at the physical point to generate Nf = 2 and Nf = 2 + 1 + 1 gauge ensembles. The adaptive aggregation-based domain decomposition multigrid solver, referred to a ... More
Presented by Mr. Simone BACCHIO on 19 Jun 2017 at 14:30
Type: Parallel Session: Hadron Spectroscopy and Interactions
Track: Hadron Spectroscopy and Interactions
In this talk I will present results from our recent lattice QCD study of $N\pi$ scattering in the positive-parity nucleon channel, where the puzzling Roper resonance $N^*(1440)$ resides in experiment. Using a variety of hadron operators, that include $qqq$-like, $N\pi$ in $p$-wave and $N\sigma$ in $s$-wave, we systematically extract the excited lattice spectrum in the nucleon channel up to 1.65 ... More
Presented by Dr. Padmanath MADANAGOPALAN on 19 Jun 2017 at 15:10
Type: Poster Session: Poster Session
N=1 supersymmetric Yang-Mills theory describes interacting gauge fields and their superpartners, the spin 1/2 gluinos. A gluino mass term breaks supersymmetry softly. In the supersymmetric limit, the physical particles are expected to form supermultiplets. In our numerical simulations with gauge groups SU(2) and SU(3) we obtained results for the masses of the lowest lying bound states and som ... More
Presented by Prof. Gernot MÜNSTER on 20 Jun 2017 at 19:30
Type: Parallel Session: Physics Beyond the Standard Model
Track: Physics Beyond the Standard Model
The $N=2^\star$ Yang-Mills theory in four dimensions is a non-conformal theory that appears as a mass deformation of maximally supersymmetric N=4 Yang-Mills theory. This theory also takes part in AdS/CFT correspondence and its gravity dual is type IIB supergravity on the Pilch-Warner background. The finite temperature properties of this theory have been studied. It has been argued that at large N ... More
Presented by Dr. Anosh JOSEPH on 22 Jun 2017 at 16:00
Type: Parallel Session: Physics Beyond the Standard Model
Track: Physics Beyond the Standard Model
We present details of ongoing calculations of the low energy properties (spectrum, decay constants, elastic scattering) of SU(3) $N_f = 8$ gauge theory, as performed by the Lattice Strong Dynamics (LSD) collaboration. We will discuss systematic effects such as staggered fermion flavor breaking and finite volume corrections. We will also discuss the challenges of approaching the chiral limit in a ... More
Presented by Dr. George FLEMING on 20 Jun 2017 at 15:20
Type: Parallel Session: Weak Decays and Matrix Elements
Track: Weak Decays and Matrix Elements
We present our final results for the neutral $D$-meson mixing matrix elements of the complete set of dimension six $\Delta C=2$ local four-fermion operators from the first three-flavor lattice QCD calculation. We use a large subset of the MILC asqtad ensembles together with Fermilab charm and asqtad light valence quarks. We provide complete and detailed systematic error budgets which account for a ... More
Presented by Prof. Aida X. EL-KHADRA on 20 Jun 2017 at 16:20
Type: Plenary Session: Plenary Session - VI
For the neutron to have an electric dipole moment (nEDM), the theory of nature must have T, or equivalently CP, violation (CPV). Thus nEDM is a deep probe of novel CPV in beyond the standard model (BSM) physics. To leverage the connection between measured nEDM and novel mechanism of CPV, one requires calculation of matrix elements for CPV operators, for which lattice QCD can play important role. I ... More
Presented by Dr. Boram YOON on 22 Jun 2017 at 11:15
Type: Poster Session: Poster Session
I will provide an update on HPQCD second-generation B-physics calculations using improved NRQCD b quarks and HISQ light quarks on the MILC n_f=2+1+1 gauge configurations. The configurations include the effect of HISQ sea quarks with a range of light quark masses going down to the physical point for a range of lattice spacing values. Results include B and Bs mixing matrix elements and tests of ... More
Presented by Prof. Christine DAVIES on 20 Jun 2017 at 20:30
Type: Parallel Session: Software Development
Track: Software Development
I will discuss the features of the programming language Nim (https://nim-lang.org) that make it especially suitable for HPC applications. In particular I will discuss installation, metaprogramming, optimization, scripting and C/C++ interoperability. I will also give an update on the status of the lattice field theory framework QEX (https://github.com/jcosborn/qex) being developed in Nim.
Presented by James OSBORN on 23 Jun 2017 at 18:30
Type: Parallel Session: Standard Model Parameters and Renormalization
Track: Standard Model Parameters and Renormalization
We present our preliminary results of the non perturbative determination of the valence mass dependent coefficients $b_A-b_P$ and $b_m$ (as well as the ratio ${Z_P/}{(Z_S Z_A)}$) entering the flavour non singlet PCAC relation in lattice QCD with $N_f=3$ dynamical flavours. We apply the method proposed in the past for quenched approximation and $N_f=2$ case, employing a set of finite-volume ALP ... More
Presented by Dr. Giulia Maria DE DIVITIIS on 21 Jun 2017 at 12:10
Type: Parallel Session: Weak Decays and Matrix Elements
Track: Weak Decays and Matrix Elements
We study the scaling with the number of colors of the weak amplitudes mediating kaon mixing and decay, in the limit of light charm masses ($m_u = m_d = m_s = m_c$). The amplitudes are extracted directly on the lattice for $N_c = 3 - 8$ colors using twisted mass QCD. It is shown that the (subleading) $1/N_c$ corrections to $\hat B_K$ are small and that the naive $N_c \to \infty$ limit, $\hat B_ ... More Presented by Andrea DONINI on 21 Jun 2017 at 11:50 Type: Parallel Session: Standard Model Parameters and Renormalization Track: Standard Model Parameters and Renormalization We report on non-perturbative computations of the improvement coefficient$c_{\rm V}$and the renormalization factor$Z_{\rm V}$of the vector current in three-flavour O($a$) improved lattice QCD with Wilson quarks and tree-level Symanzik improved gauge action. To reduce finite quark mass effects, our improvement and normalization conditions exploit massive chiral Ward identities formulated in the ... More Presented by Dr. Jochen HEITGER on 21 Jun 2017 at 11:50 Type: Parallel Session: Standard Model Parameters and Renormalization Track: Standard Model Parameters and Renormalization We report on progress in our programme of non-perturbative improvement and renormalization of operators composed of Wilson fermions based on correlators in position space. We concentrate on the CLS$N_f=2+1$ensembles. We discuss an updated determination of$b_J$and$\tilde{b}_J$improvement coefficients. We introduce a new strategy for non-perturbative renormalization which alleviates the wind ... More Presented by Dr. Piotr KORCYL on 21 Jun 2017 at 11:30 Type: Parallel Session: Standard Model Parameters and Renormalization Track: Standard Model Parameters and Renormalization We present our studies of renormalization constants of non-singlet overlap quark bilinear opertors on 2+1-flavor domain wall configurations. The renormalization is performed in RI/MOM and RI/SMOM schemes. We compute the scale-independent renormalization constant for the axial vector current via the Ward identity both in the two schemes and obtain other RCs from$Z_A$. We compare the difference ... More Presented by Mr. YUJIANG BI on 21 Jun 2017 at 12:30 Type: Parallel Session: Weak Decays and Matrix Elements Track: Weak Decays and Matrix Elements Semileptonic decays of$B_s$mesons allow to explore new, independent channels to determine the CKM matrix elements$|V_{ub}|$and$|V_{cb}|$. In the past such determinations were hampered by the paucity of experimental data. In light of the large number of$B_s$mesons recorded by the LHCb experiment however such determinations are becoming feasible but require nonperturbative input in the form o ... More Presented by Dr. Oliver WITZEL on 19 Jun 2017 at 15:30 Type: Parallel Session: Hadron Structure Track: Hadron Structure We report recent progress in nonperturbative renormalization of the hadron quasi-distributions obtained through large-momentum effective theory (LaMET). We discuss the effects of the renormalization the quasi-distribution; final results converted to$\overline{MS}$are shown. Presented by Prof. Huey-Wen LIN on 20 Jun 2017 at 16:00 Type: Parallel Session: Hadron Structure Track: Hadron Structure We present results for the isovector axial, (induced) pseudoscalar, electric, and magnetic form factors of the nucleon. The calculation was done using MILC 2+1+1-flavor HISQ ensembles with three lattice spacings 0.12, 0.09, 0.06 fm and three pion masses, approximately, 310, 220, 130 MeV. The same calculation is performed with the 2+1-flavor clover ensembles with, approximately, 300 and 190 MeV pio ... More Presented by Dr. Yong-Chull JANG on 19 Jun 2017 at 14:50 Type: Parallel Session: Hadron Structure Track: Hadron Structure We report on an analysis of the average quark momentum fraction of the nucleon and related quantities using$N_f=2+1$Wilson fermions. Computations are performed on four CLS ensembles covering three values of the lattice spacing at pion masses down to$M_\pi \approx 200\,\mathrm{MeV}$. Several source-sink separations ($\sim 1.0\,\mathrm{fm}$to$\sim 1.4\,\mathrm{fm}$) are used to assess excited-s ... More Presented by Dr. Konstantin OTTNAD on 21 Jun 2017 at 12:50 Type: Parallel Session: Hadron Structure Track: Hadron Structure I present continuum-limit results for the scalar quark content of the nucleon computed on BMW 3-HEX ensembles. The contents are determined, from the quark-mass dependence of the nucleon mass, through the Feynman-Hellman theorem. I describe a method that avoids a separate computation of quark-mass renormalization constants. Individual up- and-down quark contents of the proton and neutron are comput ... More Presented by Dr. Christian HOELBLING on 21 Jun 2017 at 11:30 Type: Parallel Session: Hadron Structure Track: Hadron Structure The conventional approach for calculating the nucleon radius on a finite-size lattice requires interpolation of form factors in the quantized momentum transfer$Q^2$. This interpolation is model-dependent and is therefore a source of systematic uncertainty. Recently, we have presented a derivative method for computing the isovector Dirac radius and the anomalous magnetic moment of the nucleon dire ... More Presented by Nesreen HASAN on 19 Jun 2017 at 17:00 Type: Parallel Session: Hadron Structure Track: Hadron Structure We present an update on our results of nucleon form factors measured on a large-volume lattice$(8.1 \mathrm{fm})^4$at almost the physical point in 2+1 flavor QCD. The configurations are generated with the stout-smeared$\mathcal{O}(a)$improved Wilson quark action and Iwasaki gauge action at$\beta=1.82$, which corresponds to the lattice spacing of 0.085 fm. The pion mass at the simulatio ... More Presented by Mr. Natsuki TSUKAMOTO on 19 Jun 2017 at 15:50 Type: Parallel Session: Hadron Structure Track: Hadron Structure Current status of nucleon-structure calculations using the RBC and RBC+UKQCD 2+1-flavor domain-wall-fermion (DWF) dynamical lattice-QCD ensembles is reported. Presented by Dr. Shigemi OHTA on 19 Jun 2017 at 16:40 Type: Poster Session: Poster Session The use of deflation is a common technique to speed up the calculation of quark propagators for Wilson/clover or domain wall fermions. I report on numerical experiments using deflation to compute quark propagators for the HISQ improved staggered action. The method is tested on HISQ gauge configurations, generated by the MILC collaboration, with lattice spacings of 0.15 fm, with a range of volumes ... More Presented by Dr. Craig MCNEILE on 20 Jun 2017 at 20:30 Type: Parallel Session: Hadron Structure Track: Hadron Structure It is important to correct for finite-volume (FV) effects in the presence of QED, since these effects are typically large due to the long range of the electromagnetic interaction. We recently made the first lattice calculation of electromagnetic corrections to the hadronic vacuum polarisation (HVP). For the HVP, an analytical derivation of FV corrections involves a two-loop calculation which has n ... More Presented by Mr. James HARRISON on 22 Jun 2017 at 17:50 Type: Parallel Session: Chiral Symmetry Track: Chiral Symmetry In 2+1 dimensions the global U(2$N$) symmetry associated with massless fermions is broken to U($N)\otimes$U($N$) by a parity-invariant mass. I will show how to adapt the domain wall formulation to recover the U(2$N$)-invariant limit in interacting fermion models as the domain wall operation is increased. In particular, I will focus on the issue of potential dynamical mass generation in the Thirr ... More Presented by Prof. Simon HANDS on 22 Jun 2017 at 18:50 Type: Parallel Session: Vacuum Structure and Confinement Track: Vacuum Structure and Confinement In Coulomb gauge there is a longitudinal color electric field associated with a static quark-antiquark pair. We have measured the spatial distribution of this field, and find that it falls off exponentially with transverse distance from a line joining the two quarks. In other words there is a Coulomb flux tube, with a width that is somewhat smaller than that of the minimal energy flux tube assoc ... More Presented by Prof. Jeff GREENSITE on 19 Jun 2017 at 17:00 Type: Parallel Session: Theoretical Developments Track: Theoretical Developments The QCD at finite density is not well understood yet, where standard Monte-Carlo simulation suffers from sign problem. In order to overcome the sign problem, the method of Lefschetz thimble has been explored. Basically, the original sign problem can be less severe in a complexified theory due to the constancy of the imaginary part of an action on each thimble. However, so-called global sign proble ... More Presented by Shoichiro TSUTSUI on 22 Jun 2017 at 17:30 Presented by Prof. Mikko LAINE Type: Parallel Session: Weak Decays and Matrix Elements Track: Weak Decays and Matrix Elements Among the different scenarios of New Physics, those with an extended Higgs sector are examined with a lot of attention. Recent experimental observations of several anomalies in flavour physics with respect to expectations of the Standard Model further motivate the effort of phenomenologists. First, informations about the R_Ds* ratio, a test of lepton flavour universality equivalent to R_D*, al ... More Presented by Dr. Benoît BLOSSIER on 21 Jun 2017 at 09:00 Type: Parallel Session: Nonzero Temperature and Density Track: Nonzero Temperature and Density We compare the low eigenvalue spectra of the Overlap Dirac operator on sets of dynamical configurations at$\mu_I/mu_I^c$= 0.5, 1.5, 3 and 4. These were generated with dynamical staggered fermions on$24^3 \times 6$lattices with a tree-level Symanzik improved gauge action and a staggered Fermion sea quark action with two stout smearing steps and for a quark mass tuned to have the physical p ... More Presented by Prof. Rajiv V GAVAI on 20 Jun 2017 at 15:40 Type: Parallel Session: Theoretical Developments Track: Theoretical Developments We study the one-loop effective action defined by the chiral overlap operator in the 4-dimensional lattice formulation of chiral gauge theories by Grabowska and Kaplan. In the tree-level continuum limit, the left-handed component of the fermion is coupled only to the original gauge field~$A$, while the right-handed one is coupled only to~$A_\star$, which is given by the gradient flow of~$A$with i ... More Presented by Mr. Okuto MORIKAWA on 23 Jun 2017 at 16:00 Type: Parallel Session: Algorithms and Machines Track: Algorithms and Machines Experiences with optimizing the matrix-times-vector application of the Brillouin operator on the Intel KNL processor are reported. Without any adjustments to the memory layout, performances figures of 300 Gflop/s in sp and 230 Gflop/s in dp are observed. This is with Nc=3 colors, Nv=12 right-hand-sides, Nthr=256 threads, on lattices of size 32^3*64, using exclusively OMP pragmas. Interestingly, th ... More Presented by Dr. Stephan DURR on 19 Jun 2017 at 16:40 Presented by Dr. Marcus HARDT on 22 Jun 2017 at 16:00 Type: Poster Session: Poster Session Track: Theoretical Developments Common lore suggests that no well-defined order parameters exist in$N$-color QCD with massive quarks which are non-trivial at zero baryon density. However, such order parameters do exist when there are$n_f$quark flavors with a common mass and$d\equiv{\rm gcd}(n_f,N) > 1$. Such theories have$Z_d$color-flavor center symmetry arising from intertwined color center transformations and cyclic flav ... More Presented by Mr. Aleksey CHERMAN on 20 Jun 2017 at 20:30 Type: Parallel Session: Applications Beyond QCD Track: Applications Beyond QCD Using the complex Langevin method for stochastic quantization, we implement a particle-number projection technique on the partition function of spin-1/2 fermions at finite temperature on the lattice. In this presentation, we discuss the method and show results for the free energy of polarized systems of Nup+Ndown particles in a finite volume, as well as virial coefficients of various orders. Presented by Christopher SHILL on 22 Jun 2017 at 16:00 Type: Parallel Session: Hadron Structure Track: Hadron Structure Recently, methods that allow for the computation of parton distribution functions in lattice QCD have been proposed. In particular, it has been argued that time-local, and spatially non-local Euclidean matrix elements can be used as probes of hadronic structure and, in certain limits, light-cone parton distribution functions can be obtained. However, approaching these limits presents both numerica ... More Presented by Prof. Kostas ORGINOS on 20 Jun 2017 at 15:40 Type: Plenary Session: Plenary Session - IV Analyses of LHC (and other!) experiments require robust and statistically accurate determinations of the structure of the proton, encoded in the parton distribution functions (PDFs). The standard description of hadronic processes relies on factorization theorems, which allow a separation of process-dependent short-distance physics from the universal long-distance structure of the proton. Trad ... More Presented by Prof. Luigi DEL DEBBIO on 20 Jun 2017 at 11:15 Type: Parallel Session: Hadron Structure Track: Hadron Structure The partonic and electromagnetic structure of the proton has been studied extensively over the past few decades. There is now extensive knowledge of the longitudinal momentum distributions of quarks and gluons in the proton. Nevertheless, there are gaps in the experimental coverage and it is hence highly desired to have robust results from numerical simulations in lattice QCD — in addition to es ... More Presented by Prof. Ross YOUNG on 20 Jun 2017 at 17:50 Type: Parallel Session: Nonzero Temperature and Density Track: Nonzero Temperature and Density We propose a path modification method to evade the sign problem in the Monte-Carlo calculations for complex actions. Among many approaches to the sign problem, the Lefschetz-thimble path-integral method and the complex Langevin method are currently considered to be promising and extensively discussed. In these methods, real field variables are complexified and the integration manifold is determ ... More Presented by Prof. Akira OHNISHI on 22 Jun 2017 at 15:40 Type: Parallel Session: Nonzero Temperature and Density Track: Nonzero Temperature and Density Ever since fast hydrodynamization has been observed in heavy ion collisions the understanding of the hot early out-of-equilibrium stage of such collisions has been a topic of intense research. We use the gauge/gravity duality to model the creation of a strongly coupled Quark-Gluon plasma in a non-conformal gauge theory. This numerical relativity study is the first non-conformal holographic simula ... More Presented by Dr. Maximilian ATTEMS on 23 Jun 2017 at 15:00 Type: Parallel Session: Software Development Track: Software Development One of the key requirements for the Lattice QCD Application Development as part of the US Exascale Computing Project is performance portability across multiple architectures. Using the Grid C++ expression template as a starting point, we report on the progress made with regards to the Grid GPU offloading strategies. We present both the successes and issues encountered in using CUDA, OpenACC and Ju ... More Presented by Dr. Meifeng LIN on 23 Jun 2017 at 15:40 Type: Parallel Session: Hadron Structure Track: Hadron Structure We present results for the renormalization of gauge invariant nonlocal fermion operators which contain a Wilson line, to one loop level in lattice perturbation theory. Our calculations have been performed for Wilson/clover fermions and a wide class of Symanzik improved gluon actions. The extended nature of such long-link' operators results in a nontrivial renormalization, in ... More Presented by Prof. Haralambos (Haris) PANAGOPOULOS on 20 Jun 2017 at 17:10 Type: Parallel Session: Hadron Structure Track: Hadron Structure Matching of the quasi parton distribution functions between continuum and lattice is addressed using lattice perturbation theory. Specifically, we use Wilson-type fermions in the analysis. The matching is done for non-local quark bilinear operators with Wilson line. We also discuss operator mixing in the renormalization for the non-local operators based on a symmetry argument. Presented by Dr. Tomomi ISHIKAWA on 20 Jun 2017 at 16:20 Type: Parallel Session: Applications Beyond QCD Track: Applications Beyond QCD Dirac Semimetals Na3Bi and Cd3As2 are recently discovered materials, which low energy electronic spectrum is described by two flavours of massless 3+1D fermions. In order to study low energy properties of these materials we formulated lattice field theory with rooted staggered fermions on anisotropic lattice. It is shown that in the limit of zero temporal lattice spacing this theory reprod ... More Presented by Mr. Andrey KOTOV on 23 Jun 2017 at 15:00 Type: Parallel Session: Applications Beyond QCD Track: Applications Beyond QCD I will present recent and ongoing investigations of a four-dimensional lattice field theory with four massless reduced staggered fermions coupled through an SU(4)-invariant four-fermion interaction. As in previous studies of four-fermion and Higgs--Yukawa models with different lattice fermion discretizations, we observe a strong-coupling phase in which the system develops a mass gap without break ... More Presented by Dr. David SCHAICH on 22 Jun 2017 at 15:00 Type: Parallel Session: Weak Decays and Matrix Elements Track: Weak Decays and Matrix Elements The leptonic decay of the charged pion in the presence of background magnetic fields is investigated using Wilson fermions. It is demonstrated that the magnetic field opens up a new channel for this decay. The magnetic field-dependence of the decay constants for both the ordinary and the new channel is determined. Using these inputs from QCD, we calculate the total decay rate perturbatively. Presented by Dr. Gergely ENDRODI on 23 Jun 2017 at 18:10 Type: Parallel Session: Hadron Structure Track: Hadron Structure One of these systematic errors in the lattice computation of the HVP contribution to muon$g-2$is that associated with the extrapolation to the physical pion mass. We investigate this extrapolation assuming lattice pion masses in the range of 200 to 400 MeV with the help of two-loop chiral perturbation theory, and find that such an extrapolation is unlikely to lead to control of this systematic ... More Presented by Prof. Maarten GOLTERMAN on 22 Jun 2017 at 16:20 Type: Parallel Session: Theoretical Developments Track: Theoretical Developments Classical real-time lattice simulations play an important role in understanding non-equilibrium phenomena in gauge theories and are used in particular to model the prethermal evolution of heavy- ion collisions. Above the Debye scale the classical Yang-Mills (CYM) theory can be matched smoothly to kinetic theory. First we study the limits of the quasiparticle picture of the CYM fields by determini ... More Presented by Mr. Jarkko PEURON on 23 Jun 2017 at 17:10 Type: Parallel Session: Software Development Track: Software Development Varying from multi-core CPU processors to many-core GPUs, the present scenario of HPC architectures is extremely heterogeneous. In this context, code portability is increasingly important for easy maintainability of applications; this is relevant in scientific computing where code changes are numerous and frequent. In this talk we present the design and optimization of a state-of-the-art producti ... More Presented by Mr. Giorgio SILVI on 23 Jun 2017 at 17:30 Type: Parallel Session: Theoretical Developments Track: Theoretical Developments A positive representation for a sample of complex densities is constructed. In particular, complex measures on a direct product of$U(1)$groups are studied. After identifying general conditions which such representations should satisfy, several concrete realisations are proposed. Their performance is illustrated in few concrete examples representing problems in abelian lattice gauge th ... More Presented by Jacek WOSIEK on 22 Jun 2017 at 17:10 Type: Parallel Session: Nonzero Temperature and Density Track: Nonzero Temperature and Density We present preliminary results f​or the phase diagram of​ effective Polyakov line actions​,​ derived from SU(3) lattice gauge theory with dynamical staggered quarks ​showing a​ line of​ ​phase transitions in the temperature-density plane. The derivation is via the method of relative weights​, the quark mass is 700 MeV,​ and the ​effective theories are solved at finite chemica ... More Presented by Roman HÖLLWIESER on 21 Jun 2017 at 12:10 Presented by Dr. Raul BRICENO on 22 Jun 2017 at 12:15 Type: Parallel Session: Theoretical Developments Track: Theoretical Developments It is an old idea to replace averages of observables with respect to complex weight by an average of its analytic continuation to complexified space with respect to some probabilistic measure. This is precisely what one would like to get from complex Langevin simulations. Unfortunately, these fail in many cases of physical interest. In my talk I will describe method of deriving positive representa ... More Presented by Mr. Błażej RUBA on 22 Jun 2017 at 17:50 Presented by Elvira GAMIZ-SANCHEZ Type: Parallel Session: Hadron Structure Track: Hadron Structure We present the current status of extracting parton distribution functions (PDFs) from the quasi-PDF approach by the European Twisted Mass Collaboration. We show our results for two ensembles of gauge field configurations, at a non-physical pion mass of around 370 MeV and preliminary results at the physical pion mass. We also discuss our recent progress in renormalization of the matrix elements for ... More Presented by Dr. Krzysztof CICHY on 20 Jun 2017 at 17:30 Type: Parallel Session: Weak Decays and Matrix Elements Track: Weak Decays and Matrix Elements We discuss the ongoing effort by the RBC & UKQCD collaborations to improve our lattice calculation of the measure of Standard Model direct CP violation, \epsilon', with physical kinematics. We present our progress in decreasing the (dominant) statistical error, which we aim to reduce by a factor of 2 within the next year, including a comparison of performance figures for our measurements on Intel ... More Presented by Dr. Christopher KELLY on 21 Jun 2017 at 13:10 Type: Parallel Session: Nonzero Temperature and Density Track: Nonzero Temperature and Density We study an RMT model for QCD at finite density using the Complex Langevin algorithm. Naive implementation of the algorithm shows convergence towards the phase quenched or quenched theory. A detailed analysis of this issue and a potential resolution of the failure of this algorithm are discussed. Among others we study the behavior of the real and imaginary parts of the action under Langevin evolu ... More Presented by Dr. Savvas ZAFEIROPOULOS on 20 Jun 2017 at 18:30 Type: Parallel Session: Nonzero Temperature and Density Track: Nonzero Temperature and Density The phase boundary of lattice QCD for staggered fermions in the$\mu_B-T$has been established via a dual representation in the strong coupling limit. Extending this phase boundary towards finite inverse gauge coupling is challenging. We present numerical simulations away from the strong coupling limit, taking into account the$O(\beta^2)$corrections via plaquette occupation numbers. This allows ... More Presented by Dr. Jangho KIM on 21 Jun 2017 at 13:10 Type: Parallel Session: Nonzero Temperature and Density Track: Nonzero Temperature and Density We investigate the properties of QCD at finite temperature and isospin chemical potential using 2+1 flavours of staggered fermions with physical quark masses. We provide updates for our results concerning the properties of the phase diagram in the approach to the continuum limit and the comparison to Taylor expansion. We also discuss our determination of the equation of state at finite isospin ch ... More Presented by Dr. Bastian BRANDT on 20 Jun 2017 at 15:20 Type: Parallel Session: Nonzero Temperature and Density Track: Nonzero Temperature and Density We investigate a two-flavor quark system with opposite chemical potentials. Simulations of these isospin systems are not hindered by the sign problem. By introducing an auxiliary parameter, it is possible to simulate in the pion condensation phase by circumventing small eigenvalues of the Dirac operator. The obtained results can then be used to gain information about systems with nonzero bary ... More Presented by Mr. Sebastian SCHMALZBAUER on 20 Jun 2017 at 15:00 Type: Parallel Session: Nonzero Temperature and Density Track: Nonzero Temperature and Density The equation of state (EoS) in 2+1 flavor QCD has recently been established in the continuum limit at the physical quark masses. The HotQCD collaboration result provides the EoS in the temperature range from 130 to 400 MeV. We extend the HotQCD equation of state to higher temperatures. We utilize the Highly Improved Staggered Quarks (HISQ) action. We perform computations at the pion mass of about ... More Presented by Dr. Alexei BAZAVOV on 21 Jun 2017 at 12:50 Type: Parallel Session: Vacuum Structure and Confinement Track: Vacuum Structure and Confinement We study the behavior across deconfinement phase transition of the chromoelectric flux tube generated by quark-antiquark sources and in correspondence of several distances between the sources. We present preliminary results for distances up to 1.33 fm and temperatures up to$1.5 T_c$. Presented by Dr. Leonardo COSMAI on 19 Jun 2017 at 16:40 Type: Poster Session: Poster Session The framework of shifted boundary conditions has proven to be a very powerful tool for the study of thermal quantum field theories. For instance, it has been considered for the determination of the equation of state of the Yang-Mills theory with high accuracy. The set-up of shifted boundary conditions can be generalized to QCD and it is expected to lead to a similar breakthrough. We present result ... More Presented by Dr. Mattia DALLA BRIDA on 20 Jun 2017 at 19:30 Type: Parallel Session: Software Development Track: Software Development We will present the QCD component of the Unified European Application Benchmark Suite (UEABS). The UEABS is an initiative of PRACE to create and maintain a benchmark suite of application kernels representative of the European scientific computing landscape. Several kernels have been included based on publicly available software packages from various lattice QCD collaborations, including BQCD, open ... More Presented by Dr. Jacob FINKENRATH on 22 Jun 2017 at 15:20 Type: Plenary Session: Plenary Session - II Many-body quantum systems are very hard to describe and simulate in general, since the dimension of the state space grows exponentially with the number of particles, volume, etc. Cold atomic systems may help us in that task, as one can in principle engineer the interactions among the atoms to emulate many-body quantum problems. So far, this possibility has been mainly addressed in the context of ... More Presented by Ignacio CIRAC on 19 Jun 2017 at 11:15 Type: Parallel Session: Theoretical Developments Track: Theoretical Developments Machine learning has been a fast growing field of research in several areas dealing with large datasets. We report recent progress on using RG ideas in the context of machine learning. We discuss the correspondence between principal components analysis (PCA) and RG flows across the transition for worm configurations of the 2D Ising model. More generally, we discuss the relationship between ... More Presented by Prof. Yannick MEURICE on 23 Jun 2017 at 18:30 Type: Parallel Session: Weak Decays and Matrix Elements Track: Weak Decays and Matrix Elements A physical point simulation of the rare kaon decays$K \to \pi \ell^+ \ell^-$with 4 active flavours is demanding for two reasons: first the simulation of a physical charm quark required for the GIM mechanism requires a fine lattice, and second a large volume is needed to suppress finite volume effects. A full lattice calculation of this decay is unfeasible with existing computational resources; a ... More Presented by Mr. Andrew LAWSON on 21 Jun 2017 at 12:50 Type: Parallel Session: Chiral Symmetry Track: Chiral Symmetry We report last results on anomalous transport in the classical statistical field theory approach. In particular, we studied the chiral plasma instability (CPI) with overlap fermions. From Maxwell and anomalous transport equations, it is expected that those instabilities growth exponentially and only stop when the axial charge decays. Nevertheless, our simulations with Wilson-Dirac and overlap ferm ... More Presented by Arthur DROMARD on 22 Jun 2017 at 18:30 Type: Plenary Session: Plenary Session - III Standard lattice calculations in kaon physics are based on the evaluation of matrix elements of local operators between two single-hadron states or a single-hadron state and the vacuum. Recent progress in lattice QCD has gone beyond these standard observables. I will review the status and prospects of lattice kaon physics with an emphasis on non-leptonic K -> pi pi decay and long-distance processe ... More Presented by Xu FENG on 20 Jun 2017 at 10:00 Type: Parallel Session: Hadron Spectroscopy and Interactions Track: Hadron Spectroscopy and Interactions We obtain the short-distance limit behavior of the nonperturbative definitions, in terms of Wilson loops, of the$1/m$potential and of the$1/m^2$spin-independent velocity-dependent heavy quarkonium potentials, with${\cal O}(\alpha^3)$and${\cal O}(\alpha^2)$accuracy, respectively. These results require a non-perturbative evaluation of ultrasoft effects. The outcome can be compared with latt ... More Presented by Dr. Antonio PINEDA on 23 Jun 2017 at 15:40 Type: Parallel Session: Applications Beyond QCD Track: Applications Beyond QCD Dirac semimetal has a massless Dirac fermion protected by discrete symmetries. Under the external magnetic field, the chiral magnetic effect shows a peculiar behavior induced by the quantum anomaly. In strong magnetic field and exact massless limit, the intra-corn transition does not occur because of the helicity conservation. In exact massless limit, the transport property is dictated by the inte ... More Presented by Ms. Aya KAGIMURA on 23 Jun 2017 at 15:40 Type: Poster Session: Poster Session We perform a pilot study of the perturbative renormalization of a Supersymmetric gauge theory with matter fields on the lattice. As a specific example, we consider Supersymmetric N =1 QCD (SQCD). We study the self-energies of all particles which appear in this theory, as well as the renormalization of the coupling constant. To this end we compute, perturbatively to one-loop, the relevant two-point ... More Presented by Dr. Marios COSTA on 20 Jun 2017 at 19:30 Type: Parallel Session: Nonzero Temperature and Density Track: Nonzero Temperature and Density Lattice QCD, involving a large number of degrees of freedom, relies on the applicability of Monte Carlo methods. The presence of complex weights in the study of QCD at finite baryonic density, introduces the sign (or phase problem) in this context and is a mayor impediment for faster progress in this field. In addition to standard reweighting, several approaches have been tried to sort this ... More Presented by Prof. Lorenzo Luis SALCEDO on 22 Jun 2017 at 18:50 Type: Parallel Session: Nonzero Temperature and Density Track: Nonzero Temperature and Density Nowadays GPU is used as main coprocessor to perform all mathematical operations inside numerical simulations of the lattice QCD. Using GPGPU techniques we developed the code to study QCD phase transition line in the canonical approach. The canonical approach is a powerful tool to investigate sign problem in LQCD. The central part of the canonical approach is the fugacity expansion of the grand ... More Presented by Mr. Vladimir GOY on 23 Jun 2017 at 17:10 Type: Parallel Session: Physics Beyond the Standard Model Track: Physics Beyond the Standard Model We present preliminary results on the lattice simulation of an SU(2) gauge theory with two fermion flavors and one strongly interacting scalar field, all in the fundamental representation of SU(2). The motivation for this study comes from the recent proposal of "fundamental" partial compositeness models featuring strongly interacting scalar fields in addition to fermions. Here we describe the lat ... More Presented by Ms. Arianna TONIATO on 20 Jun 2017 at 18:10 Type: Poster Session: Poster Session Track: Standard Model Parameters and Renormalization We investigate the SU(3) Yang Mills theory at small gradient flow time and at short distances. Lattice spacings down to a=0.015fm are simulated with open boundary conditions to allow topology to flow in and out. We study the behavior of the action density E(t) close to the boundaries, the feasibility of the small flow time expansion and the extraction of the$\Lambda$-parameter from the stati ... More Presented by Mr. Rainer SOMMER on 20 Jun 2017 at 19:30 Type: Parallel Session: Chiral Symmetry Track: Chiral Symmetry Using the Sigma model to explore the lowest order pseudoscalar spectrum with SU(3) breaking, I consider an additional exact "taste" symmetry to mimic species doubling. I find that rooting replicas of a valid approach such as Wilson fermions reproduces the desired physical spectrum. In contrast, extra symmetries of the rooted staggered approach leave spurious states and a flavor ... More Presented by Dr. Michael CREUTZ on 20 Jun 2017 at 17:10 Type: Parallel Session: Physics Beyond the Standard Model Track: Physics Beyond the Standard Model We present our final results for the SU(3) sextet model with the non-improved Wilson fermion discretization. We find evidence for several phases of the lattice model, including a bulk phase with broken chiral symmetry. We study the transition between the bulk and weak coupling phase which corresponds to a significant change in the qualitative behavior of spectral and scale setting observables. ... More Presented by Prof. Claudio PICA on 20 Jun 2017 at 17:50 Type: Parallel Session: Nonzero Temperature and Density Track: Nonzero Temperature and Density We overview our results on hadron spectroscopy upon truncation of the near-zero modes of the overlap Dirac operator. A density of the near-zero modes is directly related to the quark condensate. Apriori their truncation should lead to SU(2)_L * SU(2)_R restoration. However a degeneracy that is larger than SU(2)_L*SU(2)_R*U(1)_A is observed. This symmetry turnes out to be SU(4) that includes ... More Presented by Prof. Leonid GLOZMAN on 21 Jun 2017 at 12:10 Type: Parallel Session: Physics Beyond the Standard Model Track: Physics Beyond the Standard Model Lowest lying gluonia of a pure gauge SU(N) theory with$N = N_d$being the number of dark colors provides a viable, very attractive and simple idea for the dark matter. Indeed it gives a natural explanation for the only compelling evidence for dark matter we have, namely via gravitational lensing and simultaneously readily accounts for the difficulty we are experiencing in finding direct evidenc ... More Presented by Amarjit SONI on 23 Jun 2017 at 15:40 Type: Parallel Session: Hadron Spectroscopy and Interactions Track: Hadron Spectroscopy and Interactions On the basis of the L¥"uscher's finite volume formula, a simple test (sanity check) is introduced and applied to inspect the recent claims of the existence of the nucleon-nucleon ($NN$) bound state(s) for heavy quark masses in lattice QCD. We show that the consistency between the scattering phase shifts at$k^2 > 0$and/or$k^2 < 0$obtained from the lattice data and the behavior of phase s ... More Presented by Prof. Sinya AOKI on 22 Jun 2017 at 18:30 Type: Parallel Session: Weak Decays and Matrix Elements Track: Weak Decays and Matrix Elements We present a lattice determination of the vector and scalar form factors of the$D \to \pi(K) \ell \nu$semileptonic decays, which are relevant for the extraction of the CKM matrix elements$|V_{cd}|$and$|V_{cs}|$from experimental data. Our analysis is based on the gauge configurations produced by the European Twisted Mass Collaboration with$N_f = 2 + 1 + 1$flavors of dynamical quarks. We sim ... More Presented by Mr. Giorgio SALERNO on 20 Jun 2017 at 17:50 Type: Poster Session: Poster Session We study the scaling of observables computed with an$N_f=2+1+1$fully-twisted tmQCD valence action on$N_f=2+1$CLS ensembles. Particular attention is given to relative cutoff effects in basic quantities such as quark and meson masses and decay constants, as well as to isospin splitting of pseudoscalar mesons. Presented by Mr. Javier UGARRIO MUÑOZ on 20 Jun 2017 at 20:30 Type: Parallel Session: Hadron Spectroscopy and Interactions Track: Hadron Spectroscopy and Interactions A new implementation of estimating the two-to-two K-matrix from finite-volume energies based on the Luescher formalism is described. The method includes higher partial waves and multiple decay channels, and the fitting procedure properly includes all covariances and statistical uncertainties. The method is also simpler than previously used procedures. Formulas and software for handling total sp ... More Presented by Prof. Colin MORNINGSTAR, Dr. John BULAVA on 22 Jun 2017 at 17:30 Type: Parallel Session: Hadron Spectroscopy and Interactions Track: Hadron Spectroscopy and Interactions We derive Lüscher phaseshift formulas for both meson-meson and meson-baryon scattering according to the symmetry of lattices elongated in one of the dimensions. Boosting in the elongated direction is also considered. The results are compared with those on the cubic lattice. Presented by Prof. Frank LEE on 23 Jun 2017 at 15:00 Type: Plenary Session: Plenary Session - I Scientific and personal recollections of Roberto Petronzio Presented by Giorgio PARISI on 19 Jun 2017 at 09:30 Type: Parallel Session: Hadron Structure Track: Hadron Structure A method to probe second order electroweak interactions in light nuclei is proposed and explored with a focus on double-β decay. The potential importance of short-distance nuclear effects in double-β decay is assessed using a lattice QCD calculation of the nn→pp transition and effective field theory methods. These effects, encoded in the isotensor axial polarisability, are found at the unphysi ... More Presented by William DETMOLD on 23 Jun 2017 at 16:00 Type: Parallel Session: Nonzero Temperature and Density Track: Nonzero Temperature and Density We present new results of full QCD at nonzero chemical potential. In PRD 92, 094516 (2015) the complex Langevin method was shown to break down when the inverse coupling decreases and enters the transition region from the deconfined to the confined phase. We found that the stochastic technique used to estimate the drift term can be very unstable for indefinite matrices. This may be avoided by using ... More Presented by Dr. Jacques BLOCH on 20 Jun 2017 at 17:10 Type: Parallel Session: Weak Decays and Matrix Elements Track: Weak Decays and Matrix Elements We report on a calculation of$B_c \to \eta_c l \nu$and$B_c \to J/\psi l \nu$semileptonic decays, using both NRQCD effective theory and a highly improved relativistic (HISQ) formalism at multiple lattice spacings down to$a = 0.045$fm to treat the$b$quark. In both formalisms we are able to obtain a signal across the full kinematic range, and good quantitative agreement is seen between the ... More Presented by Dr. Andrew LYTLE on 20 Jun 2017 at 15:00 Type: Parallel Session: Weak Decays and Matrix Elements Track: Weak Decays and Matrix Elements We present the status of an ongoing lattice-QCD calculation of form factors for exclusive semileptonic decays of$B$mesons with both charged currents ($B\to\pi\ell\nu$,$B_s\to K\ell\nu$) and neutral currents ($B\to\pi\ell^+\ell^-$,$B\to K\ell^+\ell^-$). The results are important for constraining or revealing physics beyond the Standard Model. This work uses MILC's (2+1+1)-flavor ensembles, with ... More Presented by Andreas KRONFELD on 19 Jun 2017 at 14:30 Type: Parallel Session: Weak Decays and Matrix Elements Track: Weak Decays and Matrix Elements We discuss a mixed-action approach in which sea quarks are regularized using non-perturbatively$O(a)$improved Wilson fermions, while an$N_f=2+1+1$fully-twisted tmQCD action is used for valence quarks. In this setup automatic O(a) improvement is preserved for valence observables, apart from small residual O(a) effects from the sea. An optimal strategy for matching sea and valence is set up, and ... More Presented by Mr. Jose Angel ROMERO JURADO on 23 Jun 2017 at 17:10 Type: Parallel Session: Nonzero Temperature and Density Track: Nonzero Temperature and Density Simulating thimble regularization of lattice field theory can be tricky when more than one thimble is to be taken into account. A couple of years ago we proposed a solution for this problem. More recently this solution proved to be effective in the case of 0+1 dimensional QCD. A few lessons we can learnt, including the role of symmetries and general hints on algorithmic solutions. We also p ... More Presented by Prof. Francesco DI RENZO on 21 Jun 2017 at 10:00 Type: Parallel Session: Algorithms and Machines Track: Algorithms and Machines We present the tuning strategy for the generation of an ensemble of$N_f=2+1+1$twisted mass fermions with a clover term at maximal twist that ensures automatic${\cal O}(a)$-improvement. The target lattice is of size$64^3\times 128$with a lattice spacing of$a\sim 0.08$~fm. We show preliminary results on the pseudoscalar masses and decay constants. Presented by Dr. Jacob FINKENRATH on 20 Jun 2017 at 18:50 Type: Parallel Session: Applications Beyond QCD Track: Applications Beyond QCD The influence of lattice structure defects on phase transition phenomena was studied in framework of 2D spin model. Effective mass of defect was proposed for investigation of conformal properties of the model at critical point. The volume dependence of defect's mass at critical point and the Critical Casimir interaction of two defects were studied. It was shown that this Casimir interaction is at ... More Presented by Dr. Oleg PAVLOVSKY on 23 Jun 2017 at 17:10 Type: Parallel Session: Software Development Track: Software Development We present preliminary results from dynamical simulations of QCD in isolation, as well as QCD coupled to QED, with C* boundary conditions. In finite volume, the use of C* boundary conditions allows for a gauge invariant and local formulation of QED without zero modes We start with an overview of the simulation code and its features. In particular we discuss the implementation of the C* boundary ... More Presented by Mr. Martin HANSEN on 22 Jun 2017 at 17:50 Type: Parallel Session: Software Development Track: Software Development Filtering algorithms for two degenerate quark flavours have advanced to the point that, in 2+1 flavour simulations, the cost of the strange quark is significant compared with the light quarks. This makes efficient filtering algorithms for single flavour actions highly desirable, in particular when considering 1+1+1 flavour simulations for QED+QCD. Here we discuss two methods for filtering the RHMC ... More Presented by Dr. Waseem KAMLEH on 22 Jun 2017 at 18:10 Type: Poster Session: Poster Session In this work we present the perturbative computation of the difference between the renormalization factors of flavor singlet and nonsinglet bilinear quark operators (scalar, pseudoscalar, vector, axial vector and tensor) on the lattice. Nonperturbative estimates of the renormalization factors for the singlet operators are notoriously difficult to obtain via numerical simulations, due to the presen ... More Presented by Mr. Gregoris SPANOUDES on 20 Jun 2017 at 19:30 Type: Parallel Session: Nonzero Temperature and Density Track: Nonzero Temperature and Density We discuss the canonical formulation of the Z(3) Potts model and its relation to heavy-dense QCD at fixed baryon number. By taking into account the local quark occupation numbers we construct a cluster algorithm which completely eliminates the fermion sign problem. In addition, the cluster formulation allows the construction of improved estimators for various observables such as the baryon chemica ... More Presented by Dr. Urs WENGER on 22 Jun 2017 at 18:30 Type: Parallel Session: Chiral Symmetry Track: Chiral Symmetry It was shown recently that in QCD like theories the chiral transition is accompained by the appearance of localized modes at the low end of the Dirac spectrum. In this talk we show that a crucial ingredient for both phenomena is the ordering of the Polyakov loop which makes the time-slices of the Dirac eigenfunctions correlated. In addition we examine a toy model (R. Frezzotti and G.C. Rossi, P ... More Presented by Dr. Ferenc PITTLER on 20 Jun 2017 at 18:30 Type: Parallel Session: Hadron Spectroscopy and Interactions Track: Hadron Spectroscopy and Interactions We present preliminary results on the positive and negative parity light and charmed baryon spectra using overlap valence quarks on MILC's 2+1+1 flavour HISQ gauge configurations. These calculations are performed on three different gauge ensembles at lattice spacings (a=0.12 fm, 0.09 fm and 0.06 fm) and for physical strange and charm quark masses. For the coarse lattice we use lightest pion mass a ... More Presented by Prof. Nilmani MATHUR on 21 Jun 2017 at 10:00 Type: Parallel Session: Physics Beyond the Standard Model Track: Physics Beyond the Standard Model We present results of lattice simulation of SU(4) gauge theory coupled to dynamical fermions in the fundamental and two-index antisymmetric representations. Such theories arise naturally in the context of models for physics beyond the Standard Model, particularly within the frameworks of composite Higgs and partial compositeness. We describe the measured spectrum of the theory and discuss some imp ... More Presented by Mr. William JAY on 19 Jun 2017 at 15:10 Type: Parallel Session: Physics Beyond the Standard Model Track: Physics Beyond the Standard Model Supersymmetric gauge theories are an important building block for extensions of the standard model. As a first step towards Super-QCD we investigate the pure gauge sector, in particular the bound states: meson-like gluinoballs, gluino-glueballs and pure glueballs. The talk will report on some first calculations performed with clover improved Wilson fermions on rather small lattices. The supersymme ... More Presented by Mr. Marc STEINHAUSER on 22 Jun 2017 at 17:50 Type: Parallel Session: Physics Beyond the Standard Model Track: Physics Beyond the Standard Model SU(3) gauge theory with 2 flavors of fermions in the two-index symmetric representation (sextet model) continues to be an interesting candidate as a composite Higgs BSM model. We report on the latest analysis and challenges of the corresponding spectroscopy. Presented by Mr. chik him WONG on 20 Jun 2017 at 17:10 Type: Parallel Session: Nonzero Temperature and Density Track: Nonzero Temperature and Density Coupling spin models to complex external fields can give rise to interesting phenomena like zeroes of the partition function (Lee-Yang zeroes, edge singularities) or oscillating propagators. Unfortunately, it usually also leads to a severe sign problem that can be overcome only in special cases; if the partition function has zeroes, the sign problem is even representation-independent at these poin ... More Presented by Mr. Tobias RINDLISBACHER on 22 Jun 2017 at 17:50 Type: Parallel Session: Theoretical Developments Track: Theoretical Developments Quantum Finite Element (QFE) seeks to generalize lattice field theory to any smooth Euclidean Riemann manifold by adapting the Finite Elements Method (FEM) in the classical limit and the geometrical characterization of Regge Calculus, supplemented by counter terms required to cancel the local scheme due to ultraviolet divergences at simplicial cut-off. High precision numerical test are presented ... More Presented by Prof. Richard BROWER on 21 Jun 2017 at 12:30 Type: Plenary Session: Plenary Session - VIII I review the status of the Complex Langevin method, which was invented to make simulations of models with complex action feasible. I discuss the mathematical justification of the procedure, as well as its limitations and open questions. Various pragmatic measures for dealing with the existing problems are described. Finally I report on the progress in the application of the method to QCD, wit ... More Presented by Dr. Erhard SEILER on 23 Jun 2017 at 11:45 Type: Parallel Session: Software Development Track: Software Development As we march towards the exa-scale, the surge of hybrid architectures, long SIMD vector lengths, low bandwidth memory subsystems, caches and networks has made it extremely challenging for Lattice QCD codes to retain both high single node performance and good scaling properties in this heterogeneous environment. In order to have access to efficient kernel implementations and the latest solvers, th ... More Presented by Dr. Bartosz KOSTRZEWA Type: Parallel Session: Vacuum Structure and Confinement Track: Vacuum Structure and Confinement We investigate the predictions of Nambu-Goto (NG) and Polyakov-Kleinert (PK) effective string actions for the Casimir energy and the width of the quantum delocalization of the string at two loop order in 4-dim pure SU(3) Yang-Mills lattice gauge theory. Intermediate and large color source separation distance, before the string breaks in full QCD, at two temperature scales are considered near the d ... More Presented by Dr. Ahmed BAKRY on 19 Jun 2017 at 17:40 Type: Plenary Session: Plenary Session - I On physically large lattices, the field variables in distant regions are only weakly correlated. A single field generated by an algorithm respecting stochastic locality may therefore provide accurate stochastic estimates of the expectation values of observables with footprints much smaller than the lattice volume. Such master-field simulations potentially allow very large lattices to be simul ... More Presented by Martin LUESCHER on 19 Jun 2017 at 10:15 Type: Parallel Session: Hadron Structure Track: Hadron Structure This presentation will examine the structure of the ground state nucleon and its finite-volume excitations from three different perspectives. Using new techniques to extract the relativistic components of the nucleon wave function, we'll explore the node structure of both upper and lower components of the nucleon wave function and reveal the manner in which a non trivial role for gluonic compon ... More Presented by Prof. Derek LEINWEBER on 19 Jun 2017 at 17:40 Type: Parallel Session: Physics Beyond the Standard Model Track: Physics Beyond the Standard Model Grand unified theories (GUTs) are an attempt to unifiy the gauge interactions of the standard model. We show that conventional perturbation theory is insufficient to correctly predict the particle spectrum in many GUTs, and how a correct result is obtained from strict gauge invariance and the Fröhlich-Morchio-Strocchi mechanism. We use lattice simulations for a toy GUT to demonstrate the above ... More Presented by Mr. Pascal TOEREK on 22 Jun 2017 at 18:10 Type: Parallel Session: Physics Beyond the Standard Model Track: Physics Beyond the Standard Model We study N = 1 supersymmetric Yang-Mills theory (SYM) on the lattice. Like QCD, SYM is confining and contains strongly bound states. Glueballs, gluino-glues, mesons and their corresponding excited states should form chiral supermultiplets if SUSY is not broken at the quantum level. We compute masses for the bound states of the two lightest supermultiplets by applying a variational method comb ... More Presented by Mr. Henning GERBER on 22 Jun 2017 at 15:40 Type: Parallel Session: Nonzero Temperature and Density Track: Nonzero Temperature and Density This report is devoted to the study of temperature dependence of bulk viscosity in SU(3)-gluodynamics. To calculate bulk viscosity wemeasured the correlation function of the trace anomaly for a set of temperatures in the region T/T_c \in (0.9, 1.5). We used multilevel algorithm which allowed us to improve the accuracy of the data. To extract the values of bulk viscosity we used two approaches: fit ... More Presented by Dr. Victor BRAGUTA on 23 Jun 2017 at 16:20 Type: Plenary Session: Plenary Session - V We recently obtained an estimate of the axion mass based on the hypothesis that axions make up most of the dark matter in the universe. A key ingredient for this calculation was the temperature-dependence of the topological susceptibility of full QCD. In the talk I summarize the calculation of the susceptibility in a range of temperatures from well below the finite temperature cross-over to a ... More Presented by Tamas G. KOVACS on 22 Jun 2017 at 10:10 Type: Parallel Session: Theoretical Developments Track: Theoretical Developments Tensor Network methods have been established over the last decade as a powerful technique for the simulation of strongly-correlated systems in low dimensions. Employing the formalism of Matrix Product States, we investigate the phase diagram of the massive Thirring model. Several distinct sectors of the total fermion number are observed. We discuss the interpretation of these sectors in the dual s ... More Presented by Mr. David Tao-Lin TAN on 23 Jun 2017 at 17:50 Type: Parallel Session: Weak Decays and Matrix Elements Track: Weak Decays and Matrix Elements We present a preliminary lattice calculation of the$D \to \pi$and$D \to K$tensor form factors$f_T$as a function of the 4-momentum transfer squared. ETMC recently computed the vector and scalar form factors$f_+(q^2)$and$f_0(q^2)$describing$D \to \pi(K) \ell \nu$semileptonic decays analyzing the vector current and the scalar density. The study of the weak tensor current, which is directl ... More Presented by Dr. Lorenzo RIGGIO on 20 Jun 2017 at 18:10 Type: Parallel Session: Applications Beyond QCD Track: Applications Beyond QCD Universality of various fermion formulations is well established in QCD-like theories that are defined around the perturbative$g^2=0$fixed point. These arguments do not apply for conformal systems that exhibit an infrared fixed point at non-vanishing$g^2$coupling. We investigate the step scaling function for systems with 10 and 12 fundamental flavors using domain wall fermions and compa ... More Presented by Prof. Anna HASENFRATZ on 23 Jun 2017 at 17:30 Type: Parallel Session: Physics Beyond the Standard Model Track: Physics Beyond the Standard Model In this contribution we lay down a lattice setup that allows for the non-perturbative study of a field theoretical model where a SU(2) fermion doublet, subjected to non-Abelian gauge interactions, is also coupled to a complex scalar field doublet via a Yukawa and an “irrelevant” Wilson-like term. Using naive fermions in quenched approximation and based on the renormalized Ward identities induc ... More Presented by Mr. Marco GAROFALO on 19 Jun 2017 at 14:30 Type: Parallel Session: Physics Beyond the Standard Model Track: Physics Beyond the Standard Model Based on a recent proposal according to which elementary particle masses could be generated by a non-perturbative dynamical phenomenon, alternative to the Higgs mechanism, we carry out lattice simulations of a model where a non-abelian strongly interacting fermion doublet is also coupled to a doublet of complex scalar fields via a Yukawa and an “irrelevant” Wilson-like term. In this pioneering ... More Presented by Petros DIMOPOULOS on 19 Jun 2017 at 14:50 Type: Parallel Session: Algorithms and Machines Track: Algorithms and Machines We present the preliminary tests on two modifications of the Hybrid Monte Carlo (HMC) algorithm. Both algorithms are designed to travel much farther in the Hamiltonian phase space for each trajectory and reduce the autocorrelations among physical observables thus tackling the critical slowing down towards the continuum limit. We present a comparison of costs of the new algorithms with the stand ... More Presented by Dr. Guido COSSU on 20 Jun 2017 at 16:00 Type: Parallel Session: Physics Beyond the Standard Model Track: Physics Beyond the Standard Model Dilaton signatures are investigated in the effective theory of the light sigma particle coupled to chiral dynamics of light Goldstone bosons. The analysis of the sextet model is based on recent results from the Lattice Higgs Collaboration. Presented by Prof. Julius KUTI on 20 Jun 2017 at 17:30 Type: Parallel Session: Physics Beyond the Standard Model Track: Physics Beyond the Standard Model The lattice studies of maximally supersymmetric Yang-Mills (MSYM) theory at strong coupling and large-N is important for verifying the gauge/gravity duality. Due to the progress made in the last decade, based on ideas from topological twisting and orbifolding, it is now possible to study these theories on the lattice while preserving an exact supersymmetry on the lattice. I will present results fr ... More Presented by Mr. Raghav Govind JHA on 22 Jun 2017 at 16:20 Type: Parallel Session: Hadron Spectroscopy and Interactions Track: Hadron Spectroscopy and Interactions The lattice QCD simulations of charmed states with$J^{PC} = 1^{++} $have been performed in this study. Particularly,$X(3872)$was investigated. The narrow state$X(3872)$was discovered by the Belle Collaboration in B decay and subsequently confirmed by the BaBar Collaboration. Both the CDF and the$D0$Collaboration saw a clear signal of inclusive$X(3872)$production in pp collision. Since ... More Presented by Ms. Olga SOLOVJEVA on 23 Jun 2017 at 17:30 Type: Plenary Session: Plenary Session - IX I will present recent progresses of LQCD on hadronic interactions which play a crucial role to understand hadron resonances and the properties of atomic nuclei. So far, two methods to extract the hadronic interactions were proposed; the Luscher's method and the HAL QCD method. These are known to be theoretically equivalent. In the first part of my talk, I will discuss baryon-baryon interactions u ... More Presented by Dr. Yoichi IKEDA on 24 Jun 2017 at 10:15 Type: Parallel Session: Hadron Spectroscopy and Interactions Track: Hadron Spectroscopy and Interactions We study tetraquark resonances with lattice QCD potentials computed for two static quarks and two dynamical quarks, the Born-Oppenheimer approximation and the emergent wave method of scattering theory. As a proof of concept we focus on systems with isospin I = 0, but consider different relative angular momenta l of the heavy b quarks. We compute the phase shifts and search for S and T matrix poles ... More Presented by Prof. Pedro BICUDO on 23 Jun 2017 at 17:10 Type: Parallel Session: Weak Decays and Matrix Elements Track: Weak Decays and Matrix Elements A number of anomalies (apparent inconsistencies with the standard model (SM)) in semileptonic decays involving a$b \rightarrow c$transition, have surfaced over the years. For example there are persistent discrepancies between experimentally observed values and SM predictions for the ratios$\mathcal{B}(B \rightarrow D(*)\tau \nu)/\mathcal{B}(B->D(*) l \nu)$($l=e$or$\mu$). This implies lepton ... More Presented by Mr. Euan MCLEAN on 19 Jun 2017 at 16:40 Type: Parallel Session: Weak Decays and Matrix Elements Track: Weak Decays and Matrix Elements We report on the status and prospects of the RBC-UKQCD collaborations' computations of$\Delta m_K$, the$K_L$-$K_S$mass difference. This calculation is an important element of our wider programme of computations of the long-distance contributions to *flavour changing neutral current* processes in kaon physics, which also includes$\epsilon_K$and the amplitudes for$K\to\pi\ell^+\ell^-$and$K^ ... More
Presented by Prof. Christopher SACHRAJDA on 21 Jun 2017 at 12:30
Type: Parallel Session: Nonzero Temperature and Density
Track: Nonzero Temperature and Density
Effective Polyakov line actions are a powerful tool to study the finite temperature behaviour of lattice gauge theories. They are much simpler to simulate than the original (3+1) dimensional LGTs and are affected by a milder sign problem. However it is not clear to which extent they really capture the rich spectrum of the original theories, a feature which is instead of great importance if one ... More
Presented by Prof. Michele CASELLE on 21 Jun 2017 at 12:30
Type: Parallel Session: Chiral Symmetry
Track: Chiral Symmetry
We present results of a study of the Chiral Separation Effect (CSE) in quenched finite-density QCD. Using a recently developed numerical method we calculate the conserved axial current for exactly chiral overlap fermions at finite density for the first time. We compute the anomalous transport coefficient for the CSE in the confining and de-confining phase and investigate possible deviations from t ... More
Presented by Mr. Matthias PUHR on 22 Jun 2017 at 18:10
Type: Poster Session: Poster Session
The symmetric momentum subtraction scheme (SMOM) has been introduced to overcome exceptional momentum flows. However, it is quite restrictive to the momentum choice - the momentum squared of all legs are identical. Therefore, a generalization called interpolating momentum subtraction scheme (IMOM) has been developed, where a free parameter $\omega$ allows for more freedom in the momentum assi ... More
Presented by Dr. Holger PERLT on 20 Jun 2017 at 19:30
Type: Parallel Session: Nonzero Temperature and Density
Track: Nonzero Temperature and Density
We present results from our recent calculation of the QCD equation of state to $\mathcal{O}(\mu_B^6)$ in the baryon chemical potential $\mu_B$ using the method of Taylor expansions. Our calculations were carried out using the Highly Improved Staggered Quark action (HISQ). The strange quark mass was fixed to its physical value while the light quark mass was fixed at two values viz. $m_l/m_s=1/20$ ... More
Presented by Dr. Prasad HEGDE on 23 Jun 2017 at 18:10
Type: Plenary Session: Plenary Session - VII
I emphasize the importance of an accurate determination of the strong coupling constant for precision and discovery physics at the LHC. I review critically the main sources of experimental information on alphas, and their experimental and theoretical limitations and potential. I specifically discuss issues related to selecting possibly more reliable measurements, to discarding apparent outliers, ... More
Presented by Dr. Stefano FORTE on 23 Jun 2017 at 10:15
Type: Parallel Session: Nonzero Temperature and Density
Track: Nonzero Temperature and Density
Jarzynski's equality provides an elegant and powerful tool to compute directly differences in free-energy in Monte Carlo simulations and it can be readily extended to lattice gauge theories to compute a large set of physically interesting observables. In this talk we present a novel technique to determine the thermodynamics of strongly-interacting matter based on this relation, which allows for a ... More
Presented by Mr. Alessandro NADA on 21 Jun 2017 at 09:00
Type: Parallel Session: Hadron Spectroscopy and Interactions
Track: Hadron Spectroscopy and Interactions
We present results for the eta' meson and the topological susceptibility in Nf=2 flavour lattice QCD. The results are obtained using Wilson twisted mass fermions at maximal twist with pion masses ranging from 250 MeV down to the physical point. A comparison to literature values is performed giving a handle on discretisation effects. Eventually, the error scaling is investigated towards the physica ... More
Presented by Prof. Carsten URBACH on 20 Jun 2017 at 17:50
Type: Poster Session: Poster Session
Unlike the simple picture shown by the quark model, the origin of the proton mass based on the related experiments results are pretty complicated and challenge our understanding of the QCD physics at the non-perturbative region. I should show our recent lattice QCD results on the decomposition of the proton mass and how important the gluon components are.
Presented by Prof. Keh-Fei LIU on 20 Jun 2017 at 19:30
Type: Parallel Session: Hadron Structure
Track: Hadron Structure
In this talk, we present recent progress in our study of the electromagnetic pion form factor using gauge configurations at the physical pion mass generated by the European Twisted Mass Collaboration. By working in the Breit frame, we obtain O(a)-improved estimates of the form factor as well as the pion charge radius. Employing twisted boundary conditions, we are able to study a wide range of mo ... More
Presented by Dr. Bartosz KOSTRZEWA
Type: Parallel Session: Hadron Spectroscopy and Interactions
Track: Hadron Spectroscopy and Interactions
It has been observed that lattice QCD calculations of the nucleon mass show a strikingly linear dependence upon the pion mass such that $m_N[\textrm{MeV}] = 800 + m_\pi$ is a remarkably good _lattice- phenomenological_ estimate of the nucleon mass at a given pion mass for pion masses in the range $170 \leq m_\pi \leq 800$ MeV. If the _goodness_ of this extrapolation persists to the physical pion ... More
Presented by Dr. Andre WALKER-LOUD on 19 Jun 2017 at 15:30
Type: Parallel Session: Nonzero Temperature and Density
Track: Nonzero Temperature and Density
We extend our previous studies [PhysRevD.90.054509, PhysRevD.92.094510] of the pion quasiparticle in the low-temperature phase of two-flavor QCD with support from chiral effective theory. This includes the analysis performed on a finite temperature ensemble of size $20\times 64^3$ at $T\simeq 151$MeV and a lighter zero temperature pion mass $m\simeq 186$MeV. Furthermore, in our investigation of th ... More
Presented by Mr. Kai ZAPP on 22 Jun 2017 at 15:00
Type: Parallel Session: Hadron Spectroscopy and Interactions
Track: Hadron Spectroscopy and Interactions
Within the last year it has been proposed that an exotic tetraquark state composed of two $b$-quarks and two $\bar{b}$-quarks could exist sufficiently far below the $2\eta_b$ threshold so to be found experimentally at the LHC. Such a state would be particularly clean theoretically because of its heavy quark content and, if it really is too light to decay to $2\eta_b$, annihilation and threshold ef ... More
Presented by Dr. Ciaran HUGHES on 23 Jun 2017 at 18:10
Type: Parallel Session: Hadron Structure
Track: Hadron Structure
We report on progress on computing the quark contributions to the nucleon spin as well as the quark contributions to the nucleon mass, the sigma-terms. The present work is carried out on $N_f=2+1$ CLS ensembles of non-perturbatively improved Wilson fermions, down to a pion mass of about 220 MeV.
Presented by Prof. Gunnar BALI on 21 Jun 2017 at 12:10
Type: Plenary Session: Plenary Session - V
Lattice computations are the only first principle method capable of quantitatively assessing the topological properties of QCD at high temperature, however the numerical determination of the topological properties of QCD, especially in the high temperature phase, is a notoriously difficult problem. We will discuss the difficulties encountered in such a computation and some strategies that have bee ... More
Presented by Dr. Claudio BONATI on 22 Jun 2017 at 09:30
Type: Parallel Session: Nonzero Temperature and Density
Track: Nonzero Temperature and Density
$SU (N)$ gauge theories on compact spaces have a non-trivial vacuum structure characterised by a countable set of topological sectors and their topological charge. In lattice simulations, every topological sector need to be explored a number of times which reflects its weight in the path integral. Current lattice simulations are impeded by the so-called freezing of the topological charge problem. ... More
Presented by Mr. Adrien FLORIO on 21 Jun 2017 at 09:20
Type: Parallel Session: Nonzero Temperature and Density
Track: Nonzero Temperature and Density
In this talk we report our study on the thermal modifications of charmonia and bottomonia from spatial correlation functions at zero and nonzero momenta in quenched QCD. To accommodate the heavy quarks on the lattice we performed simulations on very fine lattices at a fixed beta value corresponding to a lattice spacing $a^{-1}\sim$22 GeV on $192^3\times 32$, $192^3\times 48$, $192^3\times 64$ and ... More
Presented by Mr. Hai-Tao SHU on 19 Jun 2017 at 17:20
Type: Poster Session: Poster Session
We study the gaps between thermodynamic quantities in the hot and cold phases of the SU(3) gauge theory at the first order phase transition point. Performing simulations on lattices with various spatial volume and lattice spacing, we calculate the energy gap (latent heat) by a method using the Yang-Mills gradient flow and compare it with that by the conventional derivative method.
Presented by Dr. Shinji EJIRI on 20 Jun 2017 at 20:30
Type: Parallel Session: Theoretical Developments
Track: Theoretical Developments
I discuss a method to define a theta-angle in 1+1D gauge theories with matter in a way which allows for a dual description without the sign problem. The method begins with non-compact gauge theory with a continuous R-valued center symmetry. By gauging the center symmetry down to U(1), a natural theta-term can be introduced through the gauge field for the center symmetry. The theory in this formula ... More
Presented by Dr. Tin SULEJMANPASIC on 23 Jun 2017 at 18:50
Type: Parallel Session: Vacuum Structure and Confinement
Track: Vacuum Structure and Confinement
We will report on a detailed study of the three-gluon vertex in four-dimensional SU(3) Yang-Mills theory employing lattice simulations with large physical volumes and high statistics, and on a preliminary ongoing study of the same vertex function in QCD simulated with 2+1 Domain Wall fermions. We will mainly focus on the very low-momenta behaviour of the 1PI vertex function, and prove that it ... More
Presented by Prof. José RODRIGUEZ-QUINTERO on 19 Jun 2017 at 15:10
Type: Parallel Session: Nonzero Temperature and Density
Track: Nonzero Temperature and Density
We study the topological charge in $N_f=2$ QCD at finite temperature using Mobius domain-wall fermions. The susceptibility $\chi_t$ of the topological charge defined either by the index of overlap Dirac operator or a gluonic operator is investigated at several values of temperature $T\ (>T_c)$ varying the quark mass. A strong suppression of the susceptibility is observed below a certain value of t ... More
Presented by Yasumichi AOKI on 19 Jun 2017 at 14:50
Type: Parallel Session: Theoretical Developments
Track: Theoretical Developments
We study the impact of the Gradient Flow on the topology in various models. The topological susceptibility is measured directly, and by the "slab method", which is based on the topological content of sub-volumes ("slabs"). The results obtained by both methods are consistent, but the impact of the Gradient Flow on the characteristic quantity of the slab method is different in 2-flavor Q ... More
Presented by Mr. Hector MEJIA-DIAZ on 23 Jun 2017 at 16:20
Type: Parallel Session: Chiral Symmetry
Track: Chiral Symmetry
We compute the topological susceptibility $\chi_t$ of 2+1-flavor lattice QCD employing dynamical Moebius domain-wall fermions, whose residual mass is kept at ∼1 MeV or smaller. In our analysis, we focus on the fluctuation of the topological charge density in a “slab” sub-volume of the simulated lattice, which was proposed by Bietenholz et al. The quark mass dependence of our results ag ... More
Presented by Dr. Hidenori FUKAYA on 22 Jun 2017 at 17:30
Type: Poster Session: Poster Session
One of the historical suggestions to tackle the strong CP problem is to take the up quark mass to zero while keeping $m_d$ finite. The $\theta$ angle is then supposed to become irrelevant, i.e. the topological susceptibility vanishes. However, the definition of the quark mass is scheme-dependent and identifying the $m_u=0$ point is not trivial, in particular with Wilson-like fermions. More specifi ... More
Presented by Dr. Julien FRISON on 20 Jun 2017 at 20:30
Type: Parallel Session: Chiral Symmetry
Track: Chiral Symmetry
The axion is one of the more interesting candidates to make the dark matter of the universe, and the axion potential plays a fundamental role in the determination of the dynamics of the axion field. Moreover, the way in which the $U(1)_A$ anomaly manifests itself in the chiral symmetry restored phase of $QCD$ at high temperature could be tested when probing the $QCD$ phase transition in relati ... More
Presented by Prof. Vicente AZCOITI on 22 Jun 2017 at 17:50
Type: Parallel Session: Weak Decays and Matrix Elements
Track: Weak Decays and Matrix Elements
I present a new technique for extracting total transition rates into final states with any number of hadrons from lattice QCD. The method involves constructing a finite-volume Euclidean four-point function whose corresponding infinite-volume spectral function gives access to the decay and transition rates into all allowed out-states. The inverse problem of calculating the spectral function is solv ... More
Presented by Dr. Daniel ROBAINA on 21 Jun 2017 at 09:40
Type: Parallel Session: Weak Decays and Matrix Elements
Track: Weak Decays and Matrix Elements
I describe applications and extensions of a new technique for determining total transition rates into multi-hadron final states using lattice QCD. I will outline the connection of our new approach to the method of Lellouch and Lüscher, which gives decay amplitudes rather than total rates but is of limited utility when many decay channels are open. The Lellouch-Lüscher relation, together with oth ... More
Presented by Maxwell T. HANSEN on 21 Jun 2017 at 10:00
Type: Parallel Session: Hadron Spectroscopy and Interactions
Track: Hadron Spectroscopy and Interactions
Progress is presented on an ongoing effort to determine pion-pion scattering amplitudes using multiple lattice spacings, pion masses, and physical volumes. The isovector elastic $p$-wave pion-pion scattering phase shift and the isovector timelike pion form factor are calculated using the stochastic LapH treatment of all-to-all quark propagators on a selection of $N_{\mathrm{f}} = 2+1$ CLS ense ... More
Presented by Dr. John BULAVA on 19 Jun 2017 at 17:20
Type: Plenary Session: Plenary Session - IV
We report on a lattice QCD calculation of the nucleon axial charge, $g_A$, using Mobius Domain-Wall fermions solved on the dynamical $N_f=2+1+1$ HISQ ensembles after they are smeared using the gradient-flow algorithm. The calculation is performed with three pion masses, $m_\pi\sim\{310,220,130\}$ MeV. Three lattice spacings ($a\sim\{0.15,0.12,0.09\}$ fm) are used with the heaviest pion mass, whi ... More
Presented by Dr. Chia Cheng CHANG on 20 Jun 2017 at 12:15
Type: Parallel Session: Hadron Spectroscopy and Interactions
Track: Hadron Spectroscopy and Interactions
Results are presented from an ongoing study of the $\rho$ resonance. We use the distillation approach in order to create correlator matrices involving $\rho$ and $\pi\pi$ interpolators. The study is done in a centre-of-mass frame and several moving frames. We are able to extract energy levels by solving the GEVP of those correlator matrices. The current study focusses on CLS 2-flavour lattices wi ... More
Presented by Mr. Felix ERBEN on 19 Jun 2017 at 17:40
Type: Poster Session: Poster Session
We present an exploratory study of leading isospin breaking effects in mesonic masses using $O(a)$ improved Wilson fermions. Isospin symmetry is explicitly broken by distinct masses and electric charges of the up and down quarks. In order to be able to make use of existing isosymmetric QCD gauge ensembles we apply reweighting techniques. The path integral describing QCD+QED is expanded perturbativ ... More
Presented by Andreas RISCH on 20 Jun 2017 at 20:30
Type: Parallel Session: Hadron Spectroscopy and Interactions
Track: Hadron Spectroscopy and Interactions
We present results on the light hadron spectrum and related quantities, obtained by RQCD on $N_f=2+1$ flavour CLS ensembles of non-perturbatively order-a improved Wilson fermions, employing open boundary conditions in time, Configurations at five different values of the lattice spacing, ranging from 0.086 fm down to below 0.04 fm, exist and many quark mass combinations are analysed, in particular ... More
Presented by Dr. Wolfgang SOELDNER on 21 Jun 2017 at 10:20
Type: Parallel Session: Theoretical Developments
Track: Theoretical Developments
We describe our studies of truncation of the twisted formulation of four-dimensional lattice N=4 super Yang-Mills from U(N) gauge theory to SU(N) gauge theory. One approach involves imposing the constraint that the complexified bosonic link matrices are elements of the group SL(N,C). We describe how this is consistent with SU(N) lattice gauge invariance. The second approach achieves this objective ... More
Presented by Prof. Joel GIEDT on 21 Jun 2017 at 09:20
Type: Parallel Session: Physics Beyond the Standard Model
Track: Physics Beyond the Standard Model
Supersymmetry is one of the possible scenarios for physics beyond the standard model. The building blocks of this scenario are supersymmetric gauge theories, which exhibit interesting non-perturbative effects. In our work, we study the dimensional reduced N=1 Super Yang Mills theory, namely two dimensional N=2 Super Yang Mills theory. In our lattice formulation we break supersymmetry and ch ... More
Presented by Mr. Daniel AUGUST on 22 Jun 2017 at 17:30
Type: Parallel Session: Physics Beyond the Standard Model
Track: Physics Beyond the Standard Model
We report on a non-perturbative study of D=2 N=(2,2) super QCD. Our lattice formulation retains an exact supersymmetry at non-zero lattice spacing. In addition to the gauge bosons and fermions found in a U(N_c) super Yang-Mills theory this model also contains N_f fermions and scalars transforming in the fundamental representation of the gauge group. We present evidence that the exact supersymmetr ... More
Presented by simon CATTERALL on 22 Jun 2017 at 17:10
Type: Parallel Session: Hadron Spectroscopy and Interactions
Track: Hadron Spectroscopy and Interactions
In lattice QCD, both direct and HAL QCD potential methods are employed to study hadron interactions. In the direct method, the eigen-energy of two-body system is obtained from the temporal correlation function. The scattering phase shift is calculated by Luscher's finite volume formula, which should agree with HAL QCD method. However, for two-nucleon systems at heavier pion mass, there are differ ... More
Presented by Dr. Takumi IRITANI on 22 Jun 2017 at 18:50
Type: Parallel Session: Nonzero Temperature and Density
Track: Nonzero Temperature and Density
The severe sign problem (SSP) is a longstanding challenge for high energy and solid-state theorists. In order to test new proposals to simulate physical systems with SSP it would be very useful to dispose of systems with SSP, and non trivial phase structure, the dynamics of which is well known. We study here the two-dimensional antiferromagnetic Ising model within an imaginary magnetic field, ... More
Presented by Eduardo ROYO-AMONDARAIN on 22 Jun 2017 at 18:10
Type: Parallel Session: Nonzero Temperature and Density
Track: Nonzero Temperature and Density
Recently there has been remarkable progress in solving the sign problem, which occurs in investigating statistical systems with a complex weight. The two promising methods, the complex Langevin method and the Lefschetz thimble method, share the idea of complexifying the dynamical variables, but their relationship has not been clear. Here we propose a unified formulation, in which the sign problem ... More
Presented by Prof. Jun NISHIMURA on 21 Jun 2017 at 10:20
Type: Poster Session: Poster Session
We present recent results of the indirect CP violation parameter in the neutral kaon system, $\varepsilon_K$ calculated using lattice QCD inputs including $\hat{B}_K$, $\xi_0$, $\xi_2$, $V_{us}$, $V_{cb}$, and $m_c(m_c)$.
Presented by Prof. Weonjong LEE on 20 Jun 2017 at 20:30
Type: Parallel Session: Physics Beyond the Standard Model
Track: Physics Beyond the Standard Model
We present a non perturbative study of SU(2) gauge theory with two fundamental Dirac flavours. This theory provides a minimal template which is ideal for a wide class of Standard Model extensions featuring novel strong dynamics, such as a minimal realization of composite Higgs models. We present an update on the status of the meson spectrum and decay constants based on increased statistics on our ... More
Presented by Dr. Tadeusz JANOWSKI on 20 Jun 2017 at 18:30
Type: Parallel Session: Algorithms and Machines
Track: Algorithms and Machines
A significant obstacle facing the approach to the continuum limit in lattice gauge theory calculations is the phenomena of critical slowing down in the fermion sector. The method of adaptive multigrid ($\alpha$-MG) methods offer a permanent solution to the superlinear growth in the cost of iterative Dirac matrix inversions. An exascale-ready implementation of $\alpha$-MG as a preconditioner is sui ... More
Presented by Dr. Evan WEINBERG on 19 Jun 2017 at 15:10
Type: Parallel Session: Nonzero Temperature and Density
Track: Nonzero Temperature and Density
We report on the status of ongoing investigations aiming at: locating the deconfinement critical point with standard Wilson fermions and <I>N<sub>f</sub> = 2</i> flavors towards the continuum limit (standard Columbia plot); locating the tricritical masses at imaginary chemical potential with unimproved staggered fermions at <I>N<sub>f</sub> = 2</i> (extended Columbia plot); identifying the order o ... More
Presented by Francesca CUTERI on 23 Jun 2017 at 17:30
Type: Parallel Session: Hadron Structure
Track: Hadron Structure
It is a common problem in In lattice QCD calculations of hadron masses with annihilation channel that the signal falls off in time separation while the noise remains constant. In addition, the disconnected insertion calculation in the three-point function and the calculation of the neutron electric dipole moment (nEDM) with the $\theta$ terms suffer from a noise due to the $\sqrt{V}$ fluctuation. ... More
Presented by Prof. Keh-Fei LIU on 21 Jun 2017 at 09:40
Type: Poster Session: Poster Session
In this work we present an extension of the Lüscher formalism to include the interaction of particles with spin, focusing on the scattering of two vector particles. The derived formalism will be applied to Scalar QED in the Higgs Phase, where the U(1) gauge boson acquires mass.
Presented by Mr. Fernando ROMERO-LOPEZ on 20 Jun 2017 at 19:30
Type: Parallel Session: Physics Beyond the Standard Model
Track: Physics Beyond the Standard Model
The introduction of a space-time lattice as a regulator of field theories breaks symmetries associated with continuous space-time, i.e. Poincare ́ invariance and supersymmetry. A non-zero gluino mass in the supersymmetric Yang-Mills theory causes an additional soft breaking of supersymmetry. We employ the lattice form of SUSY Ward identities, imposing that their continuum form would be recovere ... More
Presented by Mr. Sajid ALI on 22 Jun 2017 at 15:20
Type: Parallel Session: Theoretical Developments
Track: Theoretical Developments
A continuum Lagrangian can be rewritten as an equivalent lattice action of discretely labelled variables. When the discrete variables come from wavelets, new possible criteria for acceptable actions open up.
Presented by Prof. Herbert NEUBERGER on 21 Jun 2017 at 11:30
Type: Parallel Session: Weak Decays and Matrix Elements
Track: Weak Decays and Matrix Elements
In this work we present a new calculation of the Wilson Coefficients c1 and c2 of the Effective Weak Hamiltonian to all-orders in alpha_s, using lattice simulations. Given the current availability of lattice spacings we restrict our calculation to unphysically light W-bosons around 2 GeV and we demonstrate how both Wilson Coefficients can be obtained with controlled systematic uncertainties.
Presented by Dr. Mattia BRUNO on 23 Jun 2017 at 17:30
Type: Parallel Session: Physics Beyond the Standard Model
Track: Physics Beyond the Standard Model
Results are reported for the running coupling of weakly coupled conformal gauge theories on the lattice. The models are chosen to be close to the upper end of the conformal window where perturbation theory is reliable hence a fixed point is expected. The study serves as a test of how well lattice methods perform in the weakly coupled conformal cases.
Presented by Daniel NOGRADI on 20 Jun 2017 at 16:20
Type: Parallel Session: Software Development
Track: Software Development
We report the performance of Wilson and Domainwall Kernels on a new Intel Xeon Phi Knights Landing based machine named Oakforest-PACS, which is co-hosted by University of Tokyo and Tsukuba University and is currently fastest in Japan. This machine uses Intel Omni-Path for the internode network. We compare performance with several types of implementation including that makes use of the Grid l ... More
Presented by Dr. Issaku KANAMORI on 23 Jun 2017 at 17:10
Type: Parallel Session: Standard Model Parameters and Renormalization
Track: Standard Model Parameters and Renormalization
We present our result for the strong coupling constant computed from the u-d vector Hadronic Vacuum Polarisation function. We use nf=2+1 flavours of Domain Wall fermions at 3 lattice spacings, generated by the RBC-UKQCD collaboration. We identify several possible pitfalls in this method for determining the coupling and illustrate how to resolve them.
Presented by Dr. Renwick HUDSPITH on 21 Jun 2017 at 09:40
Type: Parallel Session: Weak Decays and Matrix Elements
Track: Weak Decays and Matrix Elements
We propose and apply a novel approach to determining |Vus| which uses inclusive strange hadronic tau decay data and hadronic vacuum polarization functions (HVPs) computed on the lattice. The experimental and lattice data are related through dispersion relations which employ a class of weight functions having poles at space-like momentum. Implementing this approach using lattice data generated by t ... More
Presented by Dr. Hiroshi OHKI on 23 Jun 2017 at 17:50
Type: Parallel Session: Hadron Spectroscopy and Interactions
Track: Hadron Spectroscopy and Interactions
The first principle calculation of hadron-hadron interaction is an important step toward the understanding of nuclear physics from QCD. The HAL QCD method is largely contributing to this purpose by making it possible to calculate nuclear potentials in lattice QCD. In this talk, we present results of \pi\pi potentials extracted in 2+1 flavor lattice QCD at m_\pi =410 MeV, using all-to-all propagato ... More
Presented by Mr. Daisuke KAWAI (FOR HAL QCD COLLABORATION) on 19 Jun 2017 at 16:40
Type: Parallel Session: Nonzero Temperature and Density
Track: Nonzero Temperature and Density
In this report we study the properties of the dense SU(2) QCD. The lattice simulations are carried out with improved gauge action and smaller lattice spacing as compared to our previous work. This allowed us to approach closer to the continuum limit and reach larger densities without lattice artifacts. We measured string tension and Polyakov loop as functions of chemical potential and temperatur ... More
Presented by Mr. Aleksandr NIKOLAEV on 21 Jun 2017 at 11:30