BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//CERN//INDICO//EN
BEGIN:VEVENT
SUMMARY:Lattice simulation with the Majorana positivity
DTSTART;VALUE=DATE-TIME:20170621T070000Z
DTEND;VALUE=DATE-TIME:20170621T072000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-1-31@cern.ch
DESCRIPTION:Speakers: YAMAMOTO\, Arata (University of Tokyo)\nWhile the si
gn problem of the Dirac fermion is conditioned by the positivity of a dete
rminant\, that of the Majorana fermion is conditioned by the positivity of
a Pfaffian.\nWe introduce one sufficient condition for the positivity of
a Pfaffian.\nBased on the positivity condition\, we study an effective mod
el of the Majorana edge states in condensed matter physics.\nWe also prese
nt the application to the Dirac fermion.\n\nhttps://makondo.ugr.es/event/0
/session/93/contribution/31
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/31
END:VEVENT
BEGIN:VEVENT
SUMMARY:Truncation of lattice N=4 super Yang-Mills
DTSTART;VALUE=DATE-TIME:20170621T072000Z
DTEND;VALUE=DATE-TIME:20170621T074000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-1-83@cern.ch
DESCRIPTION:Speakers: Prof. GIEDT\, Joel (Rensselaer Polytechnic Institute
)\nWe describe our studies of truncation of the twisted formulation of fou
r-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 comp
lexified bosonic link matrices are elements of the group SL(N\,C). We desc
ribe how this is consistent with SU(N) lattice gauge invariance. The secon
d approach achieves this objective dynamically by including a potential th
at drives the determinant of the link fields to unity. The latter formulat
ion allows us to make the necessary arguments which show that the violatio
n of the scalar supersymmetry in the lattice formulation due to this trunc
ation is a 1/N^2 effect. We present numerical studies in four dimensions w
hich provide concrete evidence for this conclusion\, consisting of two sup
ersymmetry Ward identities that are seen to be restored in the large N lim
it (up to 1% violations due to boundary conditions and a small soft mass
term).\n\nhttps://makondo.ugr.es/event/0/session/93/contribution/83
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/83
END:VEVENT
BEGIN:VEVENT
SUMMARY:Loop equation in Lattice gauge theories and bootstrap-like methods
DTSTART;VALUE=DATE-TIME:20170621T074000Z
DTEND;VALUE=DATE-TIME:20170621T080000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-1-112@cern.ch
DESCRIPTION:Speakers: Prof. KRUCZENSKI\, Martin (Purdue University)\nIn pr
inciple the loop equation provides a complete formulation of a gauge theor
y purely in terms of Wilson loops. In the case of lattice gauge theories t
he loop equation is a well defined equation for a discrete set of quantiti
es and can be easily solved at strong coupling either numerically or by se
ries expansion. At weak coupling\, however\, we argue that the equations a
re not well defined unless a certain set of positivity constraints is impo
sed. Using semi-definite programming we show numerically that\, for a pure
Yang Mills theory in two\, three and four dimensions\, these constraints
lead to good results for the mean value of the energy at weak coupling. Fu
rther\, the positivity constraints imply the existence of a positive defin
ite matrix whose entries are expectation values of Wilson loops. This matr
ix allows us to define a certain entropy associated with the Wilson loops
. We compute this entropy numerically and describe some of its properties.
Finally we discuss some preliminary ideas for extending the results to su
persymmetric N=4 SYM.\n\nhttps://makondo.ugr.es/event/0/session/93/contrib
ution/112
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/112
END:VEVENT
BEGIN:VEVENT
SUMMARY:4D $\\mathcal{N}=1$ SYM supercurrent in terms of the gradient flow
DTSTART;VALUE=DATE-TIME:20170621T080000Z
DTEND;VALUE=DATE-TIME:20170621T082000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-1-145@cern.ch
DESCRIPTION:Speakers: Ms. KASAI\, Aya (Kyushu University)\nThe gradient fl
ow and its small flow-time expansion provide a very versatile method to re
present renormalized composite operators in a regularization-independent m
anner. This technique has been utilized to construct typical Noether curre
nts such as the energy-momentum tensor and the axial-vector current in lat
tice gauge theory. In this paper\, we apply the same technique to the supe
rcurrent in the four-dimensional $\\mathcal{N}=1$ super Yang--Mills theory
(4D $\\mathcal{N}=1$ SYM) in the Wess--Zumino gauge. Since this approach
provides a priori a representation of the properly-normalized conserved su
percurrent\, our result should be useful for example in lattice numerical
simulations of the 4D $\\mathcal{N}=1$ SYM\; the conservation of the so-co
nstructed supercurrent can be used as a criterion for the supersymmetric p
oint toward which the gluino mass is tuned.\n\nhttps://makondo.ugr.es/even
t/0/session/93/contribution/145
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/145
END:VEVENT
BEGIN:VEVENT
SUMMARY:An Alternative Lattice Field Theory Formulation Inspired by Lattic
e Supersymmetry: an Overview.
DTSTART;VALUE=DATE-TIME:20170621T082000Z
DTEND;VALUE=DATE-TIME:20170621T084000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-1-215@cern.ch
DESCRIPTION:Speakers: Mr. D'ADDA\, Alessandro (INFN Sezione di Torino)\, P
rof. KAWAMOTO\, Noboru (Hokkaido University)\nWe propose an unconventional
formulation of lattice field theories which is quite general\, although o
riginally motivated by the quest of exact lattice supersymmetry.\nTwo long
standing problems have a solution in this context:\n1) Each degree of fre
edom 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 can be either identified\, thus removing the degeneracy\, or\, in som
e theories with extended supersymmetry\, identified with different member
s of the same supermultiplet.\n2) The derivative operator\, defined on the
lattice as a suitable periodic function of the lattice momentum\, is an a
ddittive and conserved quantity\, thus assuring that the Leibnitz rule is
satisfied. \nThis implies that the product of two fields on the lattice i
s replaced by a non-local "star product" which is however in general non-a
ssociative.\nAssociativity of the "star product" poses strong restrictions
on the form of the lattice derivative operator (which becomes the invers
e gudermannian function of the lattice momentum) and has the consequence t
hat the degrees of freedom of the lattice theory and of the continuum theo
ry are in one-to-one correspondence\, so that the two theories are eventua
lly equivalent.\nRegularization of the ultraviolet divergences on the latt
ice is not associated to the lattice spacing\, which does not act as a reg
ulator\, but may be obtained by a one parameter deformation of the lattic
e derivative\, thus preserving the lattice structure even in the limit of
infinite momentum cutoff. However this regularization breaks gauge invari
ance and a gauge invariant regularization within the lattice formulation i
s still lacking.\nAlso a consistent formulation on finite lattices is stil
l wanted\, at least in the sense that a violation of the Leibnitz rule is
unavoidable in that context.\n\nhttps://makondo.ugr.es/event/0/session/93/
contribution/215
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/215
END:VEVENT
BEGIN:VEVENT
SUMMARY:An Alternative Lattice Field Theory Formulation Inspired by Lattic
e Supersymmetry\, -Associativity and Regularization-
DTSTART;VALUE=DATE-TIME:20170621T084000Z
DTEND;VALUE=DATE-TIME:20170621T090000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-1-213@cern.ch
DESCRIPTION:Speakers: Prof. KAWAMOTO\, Noboru (Hokkaido University)\nThis
is the second talk followed to the first one of general formulation \nprop
osing a new type of lattice field theory without lattice \nchiral fermion
problem. It has been formulated by the momentum space by \nintroducing a n
ew continuum momentum on the lattice and has non-local \nnature in the coo
rdinate space. The recovery of associativity of the non-local \nproduct le
d us to this new formulation. It turned out that this non-local \nlattice
formulation is equivalent to the continuum theory and thus keeps \nall the
symmetry exact\, including lattice supersymmetry\, that the \ncorrespondi
ng continuum theory has. One may wonder: "How come the \nlattice theory be
equivalent to continuum theory if it is lattice \nregularized ?" In fact
this non-local lattice formulation is not yet \nregularized. We explain a
new type of regularization procedure for \nthis formulation. \n\nMost naiv
e regularization could be to put the system in a box. \nIn this case momen
tum becomes discrete and thus have a difficulty \nto find a solution of de
lta function of the new momentum conservation. \nWe can then consider a
modified lattice derivative operator with a \nnew regularization parameter
together with lattice constant. \nThis formulation is essentially equival
ent to the momentum cutoff \nregularization of continuum theory. \n\nA l
attice SUSY version of Ginsparg-Wilson relation requires an \ninvertibilit
y of the blocking transformation which requires specific \nform of the blo
cking transformation. This suggests us to introduce yet \na new regulariza
tion parameter in addition to the lattice constant. \nWe explicitly show h
ow these regularization procedures work for \n4-dimensional Wess-Zumino mo
del and phi^4 model. \n\nWe discuss the relation between the recovery of s
ymmetries and the \nintroduction of the regularization parameters. \nThe l
attice SUSY can be kept exact but associativity can be broken \nwith the i
ntroduction of the regularization parameters. \nThe breaking of associativ
ity generates broken gauge invariance. \nIt is\, however\, expected to rec
over in the continuum limit without \nfine tuning since the formulation is
equivalent to the continuum \ntheory in the limit.\n\nhttps://makondo.ugr
.es/event/0/session/93/contribution/213
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/213
END:VEVENT
BEGIN:VEVENT
SUMMARY:Wavelets and Lattice Field Theory
DTSTART;VALUE=DATE-TIME:20170621T093000Z
DTEND;VALUE=DATE-TIME:20170621T095000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-0-20@cern.ch
DESCRIPTION:Speakers: Prof. NEUBERGER\, Herbert (Rutgers)\nA continuum Lag
rangian can be rewritten as an equivalent lattice action of discretely la
belled variables. When the discrete variables come from wavelets\, new pos
sible criteria for acceptable actions open up.\n\nhttps://makondo.ugr.es/e
vent/0/session/93/contribution/20
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/20
END:VEVENT
BEGIN:VEVENT
SUMMARY:Abelian Color Cycle approach for the dualization of non-abelian la
ttice field theories
DTSTART;VALUE=DATE-TIME:20170621T095000Z
DTEND;VALUE=DATE-TIME:20170621T101000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-0-74@cern.ch
DESCRIPTION:Speakers: Ms. MARCHIS\, Carlotta (University of Graz)\nThe Abe
lian Color Cycle (ACC) technique is a method to dualize non-abelian lattic
e field theories.\nThe crucial step of this approach is to decompose the a
ction 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 integration of the conventional degrees of freedom th
e partition function is exactly rewritten in terms of new\, so called dual
variables. They are color fluxes around plaquettes (ACC) for the gauge de
grees of freedom\, while the dual variables for the fermion fields form mo
nomers\, dimers and loops on the lattice. The new variables have to satisf
y color flux constraints that reflect the original gauge symmetry of the t
heory. The partition function assumes the form of a strong coupling expans
ion\, where all terms are known in closed form. We present the application
of this method to pure SU(2) and SU(3) lattice gauge theories\, as well a
s its extension to including staggered fermions.\n\nhttps://makondo.ugr.es
/event/0/session/93/contribution/74
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/74
END:VEVENT
BEGIN:VEVENT
SUMMARY:Kramers-Wannier duality with Abelian Color Fluxes for the SU(2) pr
incipal chiral model
DTSTART;VALUE=DATE-TIME:20170621T101000Z
DTEND;VALUE=DATE-TIME:20170621T103000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-0-105@cern.ch
DESCRIPTION:Speakers: Prof. GATTRINGER\, Christof (University of Graz\, Au
stria)\nWe derive a full Kramers-Wannier dualization of the SU(2) principa
l chiral model. In a first step the trace and color multiplications in the
action are written explicitly\, such that only commuting numbers ("Abelia
n Color Fluxes") remain. The individual Boltzmann factors are then expande
d and the original degrees of freedom are integrated out explicitly. The e
xpansion indices become the new variables which are subject to constraints
. We show that after a suitable reorganization of the new variables the co
nstraints can be resolved by switching to the dual lattice. The resulting
dual form implements the original symmetries in an interesting geometrical
way\, which we discuss for the model at different numbers of dimensions.\
n\nhttps://makondo.ugr.es/event/0/session/93/contribution/105
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/105
END:VEVENT
BEGIN:VEVENT
SUMMARY:Status of QFE Lattice Field Theory on Spheres and Cylinders
DTSTART;VALUE=DATE-TIME:20170621T103000Z
DTEND;VALUE=DATE-TIME:20170621T105000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-0-351@cern.ch
DESCRIPTION:Speakers: Prof. BROWER\, Richard (Boston University)\nQuantum
Finite Element (QFE) seeks to generalize lattice field theory to any smoot
h Euclidean Riemann manifold by adapting the Finite Elements Method (FEM)
in the classical limit and the geometrical characterization of Regge Calc
ulus\, supplemented by counter terms required to cancel the local scheme d
ue to ultraviolet divergences at simplicial cut-off. High precision numer
ical test are presented for the 2D phi 4th theory at the Wilson-Fisher fix
ed point compared with the exact solution of the Ising CFT on the Riemann
two sphere (S2). Progress toward further tests of 3D phi 4th theory on S3
and on the R x S2 boundary of AdS is discussed as well as the challenges r
equired for including Fermionic and non-Abelian gauge fields.\n\nhttps://m
akondo.ugr.es/event/0/session/93/contribution/351
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/351
END:VEVENT
BEGIN:VEVENT
SUMMARY:Development of Grassmann higher order tensor renormalization group
DTSTART;VALUE=DATE-TIME:20170621T105000Z
DTEND;VALUE=DATE-TIME:20170621T111000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-0-171@cern.ch
DESCRIPTION:Speakers: Mr. YOSHIMURA\, Yusuke (CCS\, University of Tsukuba)
\nWe have developed Grassmann higher order tensor renormalization group (G
HOTRG) to analyze higher dimensional fermionic systems. We first apply it
to three-dimensional free Wilson fermions as a benchmark to check its effe
ctiveness. 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 improved by Grassmann higher order second
renormalization group (GHOSRG).\n\nhttps://makondo.ugr.es/event/0/session/
93/contribution/171
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/171
END:VEVENT
BEGIN:VEVENT
SUMMARY:Duals of U(N) LGT with staggered fermions
DTSTART;VALUE=DATE-TIME:20170621T111000Z
DTEND;VALUE=DATE-TIME:20170621T113000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-0-297@cern.ch
DESCRIPTION:Speakers: Dr. BORISENKO\, Oleg (Bogolyubov Institute for Theor
etical Physics)\nVarious approaches to construction of dual formulations o
f 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 formulati
on. In particular\, the dual representations are constructed 1) for pure g
auge models in all dimensions\, 2) in the strong coupling limit for the mo
dels with arbitrary number of flavours and 3) for two-dimensional U(N) QCD
with staggered fermions. Applications related to the finite temperature/d
ensity \nQCD are discussed.\n\nhttps://makondo.ugr.es/event/0/session/93/c
ontribution/297
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/297
END:VEVENT
BEGIN:VEVENT
SUMMARY:Positive Representations of a Class of Complex\, Periodic Measures
DTSTART;VALUE=DATE-TIME:20170622T151000Z
DTEND;VALUE=DATE-TIME:20170622T153000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-3-34@cern.ch
DESCRIPTION:Speakers: WOSIEK\, Jacek (Jagiellonian University)\nA positive
representation for a sample of complex densities is constructed.\nIn part
icular\, complex measures on a direct product \nof $U(1)$ groups are studi
ed. \nAfter identifying general conditions which such representations shou
ld satisfy\, several concrete \nrealisations are proposed. Their performan
ce is illustrated in few concrete examples \nrepresenting problems in ab
elian lattice gauge theories.\n\nhttps://makondo.ugr.es/event/0/session/93
/contribution/34
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/34
END:VEVENT
BEGIN:VEVENT
SUMMARY:On a modification method of Lefschetz thimbles
DTSTART;VALUE=DATE-TIME:20170622T153000Z
DTEND;VALUE=DATE-TIME:20170622T155000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-3-173@cern.ch
DESCRIPTION:Speakers: TSUTSUI\, Shoichiro (KEK\, High Energy Accelerator R
esearch Organization)\nThe QCD at finite density is not well understood ye
t\, where standard Monte-Carlo simulation suffers from sign problem. In or
der to overcome the sign problem\, the method of Lefschetz thimble has bee
n explored. Basically\, the original sign problem can be less severe in a
complexified theory due to the constancy of the imaginary part of an actio
n on each thimble. However\, so-called global sign problem which originate
s from the phase factors assigned on each thimble still remains. This prob
lem may not be negligible in a situation where a large number of thimbles
contribute to the partition function.\n\nIn [1]\, we propose a method to r
esolve the global sign problem by modifying the structure of Lefschetz thi
mbles so that only a single thimble is relevant to the partition function.
It can be shown that observables measured in the original and modified th
eories are connected by a simple formula. In this talk\, we introduce this
method and slightly generalize our previous work. We exemplify that our m
ethod works in toy models.\n\n[1] S. Tsutsui and T. M. Doi\, Phys. Rev. D9
4\, 074009 (2016)\n\nhttps://makondo.ugr.es/event/0/session/93/contributio
n/173
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/173
END:VEVENT
BEGIN:VEVENT
SUMMARY:Probabilistic representations of oscillatory integrals
DTSTART;VALUE=DATE-TIME:20170622T155000Z
DTEND;VALUE=DATE-TIME:20170622T161000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-3-352@cern.ch
DESCRIPTION:Speakers: Mr. RUBA\, Błażej (Jagiellonian University)\nIt is
an old idea to replace averages of observables with respect to complex we
ight by an average of its analytic continuation to complexified space with
respect to some probabilistic measure. This is precisely what one would l
ike to get from complex Langevin simulations. Unfortunately\, these fail i
n many cases of physical interest. In my talk I will describe method of de
riving positive representations by matching of moments. I will show simple
examples of successful constructions and argue that problem is greatly un
derdetermined.\n\nhttps://makondo.ugr.es/event/0/session/93/contribution/3
52
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/352
END:VEVENT
BEGIN:VEVENT
SUMMARY:Convergent expansions for lattice models with and without sign pro
blem
DTSTART;VALUE=DATE-TIME:20170622T161000Z
DTEND;VALUE=DATE-TIME:20170622T163000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-3-364@cern.ch
DESCRIPTION:Speakers: Dr. SAZONOV\, Vasily (LPT\, University Paris-Sud 11)
\nThe positivity of the Boltzmann weight\, needed for its probabilistic in
terpretation and for the application of the Monte Carlo method is absent f
or theories with complex actions. We propose avoiding the latter problem s
ubstituting Monte Carlo simulations by computations with convergent 'non-p
erturbative' expansions. We discuss constructions of such expansions and f
irst numerical results on the examples of $phi^4$-model at zero/non-zero c
hemical potential and lattice QED.\n\nhttps://makondo.ugr.es/event/0/sessi
on/93/contribution/364
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/364
END:VEVENT
BEGIN:VEVENT
SUMMARY:Matching Conditions in Complex Langevin Approach
DTSTART;VALUE=DATE-TIME:20170622T163000Z
DTEND;VALUE=DATE-TIME:20170622T165000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-3-394@cern.ch
DESCRIPTION:Speakers: Mr. WYRZYKOWSKI\, Adam (Jagiellonian University)\nTh
e problem of finding a positive distribution\, which corresponds to a give
n complex density in complex Langevin approach\, is studied. By the requir
ement that the moments of the positive distribution and of the complex den
sity are equal\, one can reduce the problem to solving the matching condit
ions. After imposing the positivity of the distribution\, these conditions
become a set of quadratic equations. Groebner basis approach and minimiza
tion methods were used to find its approximate solutions\, when the set of
equations is restricted to a few lowest-order moments. The problem is amb
iguous and the number of solutions rapidly increases with the number of eq
uations. For a Gaussian complex density\, these solutions are compared wit
h the exact result\, which is known in this special case.\n\nhttps://makon
do.ugr.es/event/0/session/93/contribution/394
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/394
END:VEVENT
BEGIN:VEVENT
SUMMARY:Function Support and Localization
DTSTART;VALUE=DATE-TIME:20170622T165000Z
DTEND;VALUE=DATE-TIME:20170622T171000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-3-412@cern.ch
DESCRIPTION:Speakers: Prof. HORVATH\, Ivan (University of Kentucky)\nWe ar
gue that it is possible to uniquely define function support that preserves
elementary properties of the function domain. This leads\, among other th
ings\, to rigorous and general definition of the localization property.\n\
nhttps://makondo.ugr.es/event/0/session/93/contribution/412
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/412
END:VEVENT
BEGIN:VEVENT
SUMMARY:Exponential reduction of finite volume effects with twisted bounda
ry conditions
DTSTART;VALUE=DATE-TIME:20170622T130000Z
DTEND;VALUE=DATE-TIME:20170622T132000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-2-10@cern.ch
DESCRIPTION:Speakers: Mr. CHERMAN\, Aleksey (University of Washington)\nFl
avor-twisted boundary conditions can be used for exponential reduction of
finite volume artifacts in flavor-averaged observables in lattice QCD calc
ulations with SU(Nf) light quark flavor symmetry. Finite volume artifact r
eduction 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 of flavor-twisted boundary conditions\, finite
volume artifacts for flavor-singlet observables in a hypercubic spacetime
volume are reduced to the size of finite volume artifacts in a spacetime v
olume with periodic boundary conditions that is four times larger.\n\nhttp
s://makondo.ugr.es/event/0/session/93/contribution/10
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/10
END:VEVENT
BEGIN:VEVENT
SUMMARY:Local multiboson factorization of the quark determinant
DTSTART;VALUE=DATE-TIME:20170622T132000Z
DTEND;VALUE=DATE-TIME:20170622T134000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-2-43@cern.ch
DESCRIPTION:Speakers: Dr. CÈ\, Marco (Helmholtz-Institut Mainz\, Johannes
Gutenberg-Universität Mainz)\nMany correlators in lattice QCD show an ex
ponential degradation of the signal-to-noise ratio with distance. This pro
blem can be addressed by performing *multilevel* Monte Carlo sampling. How
ever\, to date\, multilevel techniques have been limited to bosonic theori
es.\n\nTo overcome this limitation\, we developed a factorization into ind
ependent spacetime domains of the Wilson fermions determinant contribution
to the path integral of lattice QCD. We studied in detail the numerical p
roperties of the operator mediating inter-domain interactions\, and propos
ed to represent its determinant by a path integral over *multiboson* field
s\, living on the domain boundaries. On the contrary\, the intra-domain co
ntribution to the determinant is represented by ordinary pseudofermion fie
lds with suitable boundary conditions. We implemented the factorization in
a HMC algorithm that allows to update the gauge field independently in di
fferent domains.\n\nThanks to this factorization\, combined with a matchin
g domain decomposition of observables\, it is possible to perform multilev
el Monte Carlo sampling in QCD for the first time with dynamical fermions.
\n\nhttps://makondo.ugr.es/event/0/session/93/contribution/43
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/43
END:VEVENT
BEGIN:VEVENT
SUMMARY:High-order perturbative expansions in massless gauge theories with
NSPT
DTSTART;VALUE=DATE-TIME:20170622T134000Z
DTEND;VALUE=DATE-TIME:20170622T140000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-2-360@cern.ch
DESCRIPTION:Speakers: Mr. FILACI\, Gianluca (The University of Edinburgh)\
nWe investigate the possibility of using numerical stochastic perturbation
theory (NSPT) to probe high orders in the perturbative expansion of latti
ce gauge theories with massless Wilson fermions. Twisted boundary conditio
ns are used to regularise the gauge zero-mode\; the extension of these bou
ndary conditions to include fermions in the fundamental representation req
uires to introduce a smell degree of freedom. Moreover\, the mass of Wilso
n fermions is affected by an additive renormalisation: we study how to det
ermine the mass counterterms consistently at finite volume. The knowledge
of the critical masses will enable high-order perturbative computations in
massless QCD\, e.g. (as a first application) for the plaquette.\n\nhttps:
//makondo.ugr.es/event/0/session/93/contribution/360
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/360
END:VEVENT
BEGIN:VEVENT
SUMMARY:Extracting observables from lattice data in the three-particle sec
tor
DTSTART;VALUE=DATE-TIME:20170622T140000Z
DTEND;VALUE=DATE-TIME:20170622T142000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-2-52@cern.ch
DESCRIPTION:Speakers: Dr. RUSETSKY\, Akaki (HISKP\, University of Bonn)\nT
he three-particle quantization condition is derived\, using the particle-d
imer picture in the non-relativistic effective field theory. The procedure
for the extraction of various observables in the three-particle sector (t
he particle-dimer scattering amplitudes\, breakup amplitudes\, etc.) from
the finite-volume lattice spectrum is discussed in detail. As an illustrat
ion of the general formalism\, the expression for the finite-volume energy
shift of the three-body bound-state in the unitary limit is re-derived. T
he role of the three-body force\, which is essential for the renormalizati
on\, is highlighted\, and the extension of the result beyond the unitary l
imit is studied. Comparison with other approaches\, known in the literatur
e\, is carried out.\n\nhttps://makondo.ugr.es/event/0/session/93/contribut
ion/52
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/52
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hubbard-Stratonovich like transformations for few-body interaction
s
DTSTART;VALUE=DATE-TIME:20170622T142000Z
DTEND;VALUE=DATE-TIME:20170622T144000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-2-133@cern.ch
DESCRIPTION:Speakers: Mr. KOERBER\, Christopher (Forschungszentrum Juelich
)\nThrough the development of many-body methodology and algorithms\, it ha
s become possible to describe quantum systems composed of a large number o
f particles with great accuracy. Essential to all these methods is the app
lication of auxiliary fields via the Hubbard-Stratonovich transformation.
This transformation effectively reduces two-body interactions to interacti
ons of one particle with the auxiliary field\, thereby improving the compu
tational scaling of the respective algorithms. With the increasing size of
involved particles\, the relevance of collective phenomena and interactio
ns grows as well. For many theories\, e.g. Chiral Perturbation Theory\, th
e inclusion of three-body forces has become essential in order to further
increase the accuracy on the many-body level. In this seminar\, the analyt
ical framework for establishing a Hubbard-Stratonovich-like transformation
\, which allows for the systematic and controlled inclusion of contact thr
ee- and more-body interactions\, is presented.\n\nhttps://makondo.ugr.es/e
vent/0/session/93/contribution/133
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/133
END:VEVENT
BEGIN:VEVENT
SUMMARY:Plasmon mass scale and quantum fluctuations of classical fields on
a real time lattice
DTSTART;VALUE=DATE-TIME:20170623T151000Z
DTEND;VALUE=DATE-TIME:20170623T153000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-5-11@cern.ch
DESCRIPTION:Speakers: Mr. PEURON\, Jarkko (University of Jyväskylä)\nCla
ssical real-time lattice simulations play an important role in understandi
ng non-equilibrium phenomena in gauge theories and are used in particular
to model the prethermal evolution of heavy-\nion collisions. Above the Deb
ye 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 determining the plasmon mass of the system using 3 diffe
rent methods. Then we argue for the need for a numerical calculation of
a system of classical gauge fields and small linearized fluctuations\, wh
ich correspond to quantum fluctuations\, in a way that keeps the separatio
n between the two manifest. We demonstrate and test an implementation of a
n algorithm with the linearized fluctuation showing that the linearization
indeed works and that the Gauss's law is conserved.\n\nhttps://makondo.ug
r.es/event/0/session/93/contribution/11
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/11
END:VEVENT
BEGIN:VEVENT
SUMMARY:Loop-TNR analysis of CP(1) model with theta term
DTSTART;VALUE=DATE-TIME:20170623T153000Z
DTEND;VALUE=DATE-TIME:20170623T155000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-5-146@cern.ch
DESCRIPTION:Speakers: Mr. KAWAUCHI\, Hikaru (Kanazawa University)\nWe anal
yze the CP(1) model using the Loop optimization for Tensor network renorma
lization (Loop-TNR). This method makes it possible to completely remove sh
ort-range entanglement at each coarse-graining step which can not be remov
ed by the Tensor renormalization group. We compare the results of these me
thods in the presence of the theta term.\n\nhttps://makondo.ugr.es/event/0
/session/93/contribution/146
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/146
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tensor Network study of the (1+1)-dimensional Thirring model
DTSTART;VALUE=DATE-TIME:20170623T155000Z
DTEND;VALUE=DATE-TIME:20170623T161000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-5-192@cern.ch
DESCRIPTION:Speakers: Mr. TAN\, David Tao-Lin (National Chiao Tung Univers
ity)\nTensor 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 inv
estigate the phase diagram of the massive Thirring model. Several distinct
sectors of the total fermion number are observed. We discuss the interpre
tation of these sectors in the dual sine-Gordon theory.\n\nhttps://makondo
.ugr.es/event/0/session/93/contribution/192
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/192
END:VEVENT
BEGIN:VEVENT
SUMMARY:Application of tensor network method to two dimensional lattice $\
\mathcal{N}=1$ Wess$\\unicode{x2013}$Zumino model
DTSTART;VALUE=DATE-TIME:20170623T161000Z
DTEND;VALUE=DATE-TIME:20170623T163000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-5-212@cern.ch
DESCRIPTION:Speakers: Mr. SAKAI\, Ryo (Kanazawa University)\nWe study a te
nsor network formulation of the two dimensional lattice $\\mathcal{N}=1$ W
ess$\\unicode{x2013}$Zumino model with Wilson derivatives for fermions and
bosons. The tensor renormalization group allows us to compute the partiti
on function without the sign problem\, and basic ideas to obtain a tensor
network for both fermion and scalar boson systems were already given in pr
evious works. While improving them\, we have constructed a tensor network
representation of the model including the Yukawa-type interaction of Major
ana fermions and real scalar bosons. We present some numerical results.\n\
nhttps://makondo.ugr.es/event/0/session/93/contribution/212
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/212
END:VEVENT
BEGIN:VEVENT
SUMMARY:RG inspired Machine Learning for lattice field theory
DTSTART;VALUE=DATE-TIME:20170623T163000Z
DTEND;VALUE=DATE-TIME:20170623T165000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-5-390@cern.ch
DESCRIPTION:Speakers: Prof. MEURICE\, Yannick (University of Iowa)\nMachin
e learning has been a fast growing field of research in several areas \nde
aling with large datasets. We report\nrecent progress on using RG ideas in
the context of machine learning.\nWe discuss the correspondence between p
rincipal components analysis (PCA) \nand RG flows across the transition fo
r worm configurations of the 2D Ising model.\nMore generally\, we discuss
the relationship between PCA and observables in MC data and the \npossibil
ity of reduction of the number of learning parameters in supervised learni
ng \nbased on RG inspired hierarchical ansatzes.\n\nhttps://makondo.ugr.es
/event/0/session/93/contribution/390
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/390
END:VEVENT
BEGIN:VEVENT
SUMMARY:Theta-angle\, global symmetries and sign problem in compact 1+1D U
(1) gauge theories
DTSTART;VALUE=DATE-TIME:20170623T165000Z
DTEND;VALUE=DATE-TIME:20170623T171000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-5-468@cern.ch
DESCRIPTION:Speakers: Dr. SULEJMANPASIC\, Tin (Philippe Meyer Institute Ec
ole Normale Superieure)\nI discuss a method to define a theta-angle in 1+1
D 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 f
ield for the center symmetry. The theory in this formulation can be dualiz
ed in such a way so that the sign problem is avoided. I discuss briefly th
e special case of theta=pi and possible scenarios that can be tested in la
ttice simulations.\n\nhttps://makondo.ugr.es/event/0/session/93/contributi
on/468
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/468
END:VEVENT
BEGIN:VEVENT
SUMMARY:Large $N$ scaling and factorization in SU$(N)$ Yang-Mills gauge th
eory
DTSTART;VALUE=DATE-TIME:20170623T130000Z
DTEND;VALUE=DATE-TIME:20170623T132000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-4-202@cern.ch
DESCRIPTION:Speakers: Mr. GARCÍA VERA\, Miguel Francisco (DESY Zeuthen /
Humboldt University)\nThrough a careful study of smooth Wilson loop operat
ors on the lattice\, we are able to obtain very accurate confirmation of t
he $1/N^2$ scaling predicted by `t Hooft for the pure $\\mathrm{SU}(N)$ ga
uge theory. We present our results for Wilson loops smoothed with the Yang
-Mills gradient flow and matched through the scale $t_0$.\nThis allows us
to have renormalizable operators and test the $1/N^2$ scaling both at fini
te lattice spacing and in the continuum. Our results show an excellent sca
ling up to $1/N = 1/3$. Additionally\, we look into the property of factor
ization in the large $N$ limit\, and obtain very precise non-perturbative
evidence of its validity.\n\nhttps://makondo.ugr.es/event/0/session/93/con
tribution/202
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/202
END:VEVENT
BEGIN:VEVENT
SUMMARY:Generating a mass gap using Feynman diagrams in an asymptotically
free theory
DTSTART;VALUE=DATE-TIME:20170623T132000Z
DTEND;VALUE=DATE-TIME:20170623T134000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-4-110@cern.ch
DESCRIPTION:Speakers: Prof. CHANDRASEKHARAN\, Shailesh (Duke University)\n
Using the example of a two dimensional four-fermion lattice field theory\,
we show that Feynman diagrams\ncan generate a mass gap in a theory with m
assless fermions that interact via a marginally relevant coupling.\nWe sho
w this by introducing an infrared cutoff that makes the perturbation serie
s for the partition function convergent. One can then use a Monte Carlo ap
proach to sample sufficiently high orders of diagrams and thus expose the
presence of the mass gap. Finally we outline the challenges of applying th
is method to gauge theories.\n\nhttps://makondo.ugr.es/event/0/session/93/
contribution/110
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/110
END:VEVENT
BEGIN:VEVENT
SUMMARY:Atiyah-Patodi-Singer index theorem for domain-wall fermion Dirac o
perator
DTSTART;VALUE=DATE-TIME:20170623T134000Z
DTEND;VALUE=DATE-TIME:20170623T140000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-4-87@cern.ch
DESCRIPTION:Speakers: Prof. ONOGI\, Tetsuya (Osaka University)\nRecently\,
the Atiyah-Patodi-Singer(APS) index theorem attracts attention for unders
tanding physics on the surface of materials in topological phases. Althoug
h it is widely applied to physics\, the mathematical setup in original APS
index theorem is too abstract and general (allowing non-trivial metric an
d so on) and also the connection bewteen the APS boundary condition and th
e physical boundary condition on the surface of topological material is un
clear. For this reason\, in contrast to Atiyah-Singer index theorem\, deri
vation of the APS index theorem in physics language is still missing. In t
his talk\, we attempt to reformulate the APS index in a "physicist-friendl
y" way\, similar to the Fujikawa method on closed manifolds\, for our fam
iliar domain-wall fermion Dirac operator in a flat Euclidean space. We fi
nd that the APS index is naturally embedded in the determinant of domain-w
all fermions\, representing the so-called anomaly descent equations.\n\nht
tps://makondo.ugr.es/event/0/session/93/contribution/87
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/87
END:VEVENT
BEGIN:VEVENT
SUMMARY:One-loop perturbative coupling of $A$ and $A_\\star$ through the c
hiral overlap operator
DTSTART;VALUE=DATE-TIME:20170623T140000Z
DTEND;VALUE=DATE-TIME:20170623T142000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-4-141@cern.ch
DESCRIPTION:Speakers: Mr. MORIKAWA\, Okuto (Kyushu University)\nWe study t
he one-loop effective action defined by the chiral overlap operator in the
4-dimensional lattice formulation of chiral gauge theories by Grabowska a
nd Kaplan. In the tree-level continuum limit\, the left-handed component o
f 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 gra
dient flow of~$A$ with infinite flow time. In this paper\, we show that th
e continuum limit of the one-loop effective action contains local interact
ion terms between $A$ and~$A_\\star$\, which do not generally vanish even
if the gauge representation of the fermion is anomaly-free. We argue that
the presence of such interaction terms can be regarded as undesired gauge
symmetry breaking effects in the formulation.\n\nhttps://makondo.ugr.es/ev
ent/0/session/93/contribution/141
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/141
END:VEVENT
BEGIN:VEVENT
SUMMARY:Topological Susceptibility under Gradient Flow
DTSTART;VALUE=DATE-TIME:20170623T142000Z
DTEND;VALUE=DATE-TIME:20170623T144000Z
DTSTAMP;VALUE=DATE-TIME:20200328T195036Z
UID:indico-contribution-93-4-362@cern.ch
DESCRIPTION:Speakers: Mr. MEJIA-DIAZ\, Hector (Instituto de Ciencias Nucle
ares\, UNAM)\nWe study the impact of the Gradient Flow on the topology in\
n various models. The topological susceptibility is measured\n directly\,
and by the "slab method"\, which is based on the\n topological content of
sub-volumes ("slabs").\n The results obtained by both methods are consiste
nt\, but the\n impact of the Gradient Flow on the characteristic quantity\
n of the slab method is different in 2-flavor QCD and in the\n 2d O(3) mod
el. In the latter model we address in particular\n the question whether or
not the Gradient Flow leads to a finite\n continuum limit of the topologi
cal susceptibility (rescaled by\n the correlation length squared).\n\nhttp
s://makondo.ugr.es/event/0/session/93/contribution/362
LOCATION: Andalucía I
URL:https://makondo.ugr.es/event/0/session/93/contribution/362
END:VEVENT
END:VCALENDAR