# The 35th International Symposium on Lattice Field Theory

18-24 June 2017
Palacio de Congresos
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## Place

Location: Palacio de Congresos
Date: from 19 Jun 14:30 to 23 Jun 19:10

## Conveners

• 19 Jun 14:30 - 16:10
• Prof. Prelovsek, Sasa (University of Ljubljana)
• 19 Jun 16:40 - 18:00
• Dr. Shintani, Eigo (RIKEN-AICS)
• 20 Jun 17:10 - 19:10
• Prof. Lee, Frank (George Washington University)
• 21 Jun 09:00 - 11:00
• Yamazaki, Takeshi (University of Tsukuba)
• 22 Jun 15:00 - 16:40
• Prof. Luu, Thomas (Institute for Advanced Simulation 4, Forschunszentrum Jülich)
• 22 Jun 17:10 - 19:10
• Detmold, William (MIT)
• 23 Jun 15:00 - 16:40
• Wilson, David (Trinity College Dublin)
• 23 Jun 17:10 - 19:10
• Dr. Sasaki, Kenji (YITP, Kyoto University)

## Timetable | Contribution List

Displaying 41 contributions out of 41
Type: Parallel Session: 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 20/6/2017 at 16:10
Type: Parallel Session: 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 19/6/2017 at 15:00
Type: Parallel Session: 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 22/6/2017 at 15:00
Type: Parallel Session: 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 20/6/2017 at 15:10
Type: Parallel Session: 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 19/6/2017 at 13:50
Type: Parallel Session: 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 22/6/2017 at 13:40
Type: Parallel Session: 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 22/6/2017 at 14:20
Type: Parallel Session: 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 22/6/2017 at 13:20
Type: Parallel Session: 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 22/6/2017 at 15:50
Type: Parallel Session: 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 21/6/2017 at 7:40
Type: Parallel Session: 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 23/6/2017 at 14:20
Type: Parallel Session: 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 23/6/2017 at 13:20
Type: Parallel Session: 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 20/6/2017 at 16:30
Type: Parallel Session: 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 22/6/2017 at 16:10
Type: Parallel Session: 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 23/6/2017 at 14:00
Type: Parallel Session: 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 19/6/2017 at 12:50
Type: Parallel Session: 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 20/6/2017 at 17:30
Type: Parallel Session: 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 23/6/2017 at 16:30
Type: Parallel Session: 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 21/6/2017 at 8:40
Type: Parallel Session: 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 22/6/2017 at 14:00
Type: Parallel Session: 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 21/6/2017 at 7:00
Type: Parallel Session: 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 22/6/2017 at 15:10
Type: Parallel Session: 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 21/6/2017 at 7:20
Type: Parallel Session: 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 23/6/2017 at 15:50
Type: Parallel Session: 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 19/6/2017 at 12:30
Type: Parallel Session: 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
Type: Parallel Session: 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 23/6/2017 at 13:40
Type: Parallel Session: 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 22/6/2017 at 16:30
Type: Parallel Session: 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 22/6/2017 at 15:30
Type: Parallel Session: 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 23/6/2017 at 13:00
Type: Parallel Session: 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 21/6/2017 at 8:00
Type: Parallel Session: 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 23/6/2017 at 15:30
Type: Parallel Session: 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 23/6/2017 at 17:10
Type: Parallel Session: 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 20/6/2017 at 15:50
Type: Parallel Session: 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 19/6/2017 at 13:30
Type: Parallel Session: 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 23/6/2017 at 16:10
Type: Parallel Session: 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 19/6/2017 at 17:20
Type: Parallel Session: 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 19/6/2017 at 15:40
Type: Parallel Session: 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