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BEGIN:VEVENT
SUMMARY:The dual representation as a tool to check expansion methods
DTSTART;VALUE=DATE-TIME:20140218T133000Z
DTEND;VALUE=DATE-TIME:20140218T140000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9180@indico.gsi.de
DESCRIPTION:Speakers: Ydalia Delgado ()\nRewriting the partition sum in it
s dual representation allows us to solve the sign\nproblem exactly in seve
ral systems. Therefore we can use the results obtained with the dual repre
sentation as a reference test for other approaches. For example\, I will
show a comparison between the dual representation and different expansion
methods\, which are also used in full QCD at finite density.\n\nhttps://in
dico.gsi.de/event/2451/contributions/9180/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9180/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Subsets in QCD (I)
DTSTART;VALUE=DATE-TIME:20140220T151000Z
DTEND;VALUE=DATE-TIME:20140220T154000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9198@indico.gsi.de
DESCRIPTION:Speakers: Falk Bruckmann (Regensburg University)\nI present a
subset solution of the sign problem in one-dimensional QCD with various nu
mbers of flavors.\n\nhttps://indico.gsi.de/event/2451/contributions/9198/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9198/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Worm algorithms: from loops to surfaces\, from spin models to gaug
e theories
DTSTART;VALUE=DATE-TIME:20140218T140000Z
DTEND;VALUE=DATE-TIME:20140218T143000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9181@indico.gsi.de
DESCRIPTION:Speakers: Ulli Wolff (HU Berlin)\nWe discuss the obvious gener
alization of the successful 'worm' simulation methods\nfrom scalar field t
heories to abelian gauge models. Due to the geometrically\ndifferent situa
tion\, gauge simulations along these lines (so-far) still suffer \nfrom cr
itical slowing down. Other aspects like the low noise estimation\nof obser
vables -- here the Polyakov lines and partition function ratios -- \ndo ge
neralize. We exploit these to compare the 3D Z(2) gauge theory with effect
ive string models.\n\nhttps://indico.gsi.de/event/2451/contributions/9181/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9181/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Frustrated magnetism via bold diagrammatic Monte Carlo
DTSTART;VALUE=DATE-TIME:20140218T153000Z
DTEND;VALUE=DATE-TIME:20140218T160000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9182@indico.gsi.de
DESCRIPTION:Speakers: Oleg Starykh (University of Utah)\nProperties of geo
metrically frustrated spin systems in various dimensions\, geometries\, an
d temperature regimes constitute one of the main research directions of mo
dern condensed matter physics. These studies however are severely hampere
d by the infamous sign problem synonymous with frustrated geometry. \n\nHe
re I summarize key physical features of frustrated quantum antiferromagnet
\, using triangular as an example\, and then proceed to describe first suc
cessful application of the bold diagrammatic Monte Carlo technique\, based
on exact Popov-Fedotov trick of representing spin operators with fermions
\, to this important problem. I present results for the static spin correl
ation function at various temperatures and describe unexpected approximate
quantum-to-classical correspondence between short-distance behaviors of t
he quantum and classical spin models.\n\nhttps://indico.gsi.de/event/2451/
contributions/9182/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9182/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Solution to sign problems in particle-hole symmetric spin-less fer
mion systems.
DTSTART;VALUE=DATE-TIME:20140218T160000Z
DTEND;VALUE=DATE-TIME:20140218T163000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9183@indico.gsi.de
DESCRIPTION:Speakers: Shailesh Chandrasekharan (Duke University)\nWe solve
the sign problem in a class of particle-hole symmetric spin-less fermion
models using the idea of fermion bags. The solutions emerge in the Hamilto
n formulation of lattice field theory where time can be continuous. The s
olution allows us for the first time to explore quantum phase transitions
in models with a single four-component Dirac fermion in three dimensions.\
n\nhttps://indico.gsi.de/event/2451/contributions/9183/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9183/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Bold Diagrammatic Monte Carlo for Fermionic and Fermionized System
s
DTSTART;VALUE=DATE-TIME:20140218T150000Z
DTEND;VALUE=DATE-TIME:20140218T153000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9184@indico.gsi.de
DESCRIPTION:Speakers: Boris Svistunov (University of Massachusetts\, Amher
st)\nIn three different fermionic cases---repulsive Hubbard model\, resona
nt fermions\, and fermionized spins-1/2 (on triangular lattice)---we obser
ve the phenomenon of sign blessing: Feynman diagrammatic series features
finite convergence radius despite factorial growth of the number of diagra
ms with diagram order. Bold diagrammatic Monte Carlo technique allows us
to sample millions of skeleton Feynman diagrams.\nWith the universal fermi
onization trick we can fermionize essentially any (bosonic\, spin\, mixed\
, etc.) lattice system.\n\nThe combination of fermionization and Bold diag
rammatic Monte Carlo yields a universal first-principle approach to strong
ly correlated lattice systems\, provided the sign blessing is a generic fe
rmionic phenomenon.\n\nhttps://indico.gsi.de/event/2451/contributions/9184
/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9184/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Towards a description of cold and dense QCD with an effective latt
ice theory
DTSTART;VALUE=DATE-TIME:20140219T080000Z
DTEND;VALUE=DATE-TIME:20140219T083000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9185@indico.gsi.de
DESCRIPTION:Speakers: Owe Philipsen (University of Frankfurt)\nOver the la
st two years\, a 3d effective lattice theory has been developed by means o
f strong coupling and hopping expansions\, which \nis a valid description
of QCD with large quark masses and has only a mild sign problem. This cont
ribution summarises the extension of the effective theory to order kappa^4
and from one to two flavours. The theory is applied to a description of t
he nuclear liquid gas transition which is compared to the behaviour at fin
ite isospin chemical potential.\n\nhttps://indico.gsi.de/event/2451/contri
butions/9185/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9185/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Derivation and test of an effective lattice theory for finite dens
ity
DTSTART;VALUE=DATE-TIME:20140219T083000Z
DTEND;VALUE=DATE-TIME:20140219T090000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9186@indico.gsi.de
DESCRIPTION:Speakers: Jens Langelage (ETH Zuerich)\nWe briefly review the
derivation of an effective Polyakov Loop theory for finite density Lattice
QCD and discuss recent developments. As a further test of the effective t
heory\, we compute several observables numerically and compare with result
s from full (3+1)d simulations.\n\nhttps://indico.gsi.de/event/2451/contri
butions/9186/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9186/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Effective Polyakov line action and the sign problem
DTSTART;VALUE=DATE-TIME:20140219T090000Z
DTEND;VALUE=DATE-TIME:20140219T093000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9187@indico.gsi.de
DESCRIPTION:Speakers: Jeff Greensite (San Francisco State University)\nThe
"relative weights" method is used to derive the effective Polyakov line a
ction corresponding to an underlying lattice gauge theory at any chemical
potential. Results for SU(2) and SU(3) gauge theories are presented. The
motivation is that it may be easier to address the sign problem in the ef
fective model\, e.g. by reweighting or other techniques\, than in the orig
inal lattice gauge theory.\n\nhttps://indico.gsi.de/event/2451/contributio
ns/9187/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9187/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The phase diagram of QCD in the strong coupling limit\, and how to
go further
DTSTART;VALUE=DATE-TIME:20140219T100000Z
DTEND;VALUE=DATE-TIME:20140219T103000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9188@indico.gsi.de
DESCRIPTION:Speakers: Philippe de Forcrand (ETH Zurich)\nI summarize the r
esults obtained on the (mu\,T) phase diagram of\nlattice QCD with staggere
d fermions in the strong coupling limit\,\nbeta=0\, and show how to determ
ine at least the leading\, O(beta)\ncorrections.\n\nhttps://indico.gsi.de/
event/2451/contributions/9188/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9188/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gauge corrections to the Strong Coupling limit: Numerical results
DTSTART;VALUE=DATE-TIME:20140219T103000Z
DTEND;VALUE=DATE-TIME:20140219T110000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9189@indico.gsi.de
DESCRIPTION:Speakers: Wolfgang Unger (ITP Frankfurt)\nA partition function
for strong coupling lattice QCD valid at O(beta) has been derived recentl
y. We present numerical results based on the reweighting of fermionic obse
rvables to finite beta. In this way we obtain the beta-dependence of the p
hase boundary in the mu-T plane\, based on the chiral susceptibility and t
he baryon number density. We also present gauge observables such as the Po
lyakov loop correlator and Wilson loops and sketch how to obtain higher or
der corrections in general.\n\nhttps://indico.gsi.de/event/2451/contributi
ons/9189/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9189/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The Lefschetz thimbles and the sign problem
DTSTART;VALUE=DATE-TIME:20140220T130000Z
DTEND;VALUE=DATE-TIME:20140220T133000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9190@indico.gsi.de
DESCRIPTION:Speakers: Luigi Scorzato (TIFPA)\nIn this talk\, I summarize t
he Lefschetz thimble approach to the sign\nproblem of Quantum Field Theori
es. In particular\, I review its motivations\, and summarize the results o
f its first applications\n\nhttps://indico.gsi.de/event/2451/contributions
/9190/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9190/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hybrid Monte Carlo on Lefschetz Thimbles -- A study of the residua
l sign problem
DTSTART;VALUE=DATE-TIME:20140220T133000Z
DTEND;VALUE=DATE-TIME:20140220T140000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9191@indico.gsi.de
DESCRIPTION:Speakers: Yoshio Kikukawa (Institute of Physics\, the Universi
ty of Tokyo)\nWe consider a hybrid Monte Carlo algorithm which is applicab
le to lattice theories defined on Lefschetz thimbles. In the algorithm\, a
ny point (field configuration) on a thimble is parametrized uniquely by th
e flow-direction and the flow-time defined at a certain asymptotic region
close to the critical point\, and it is generated by solving the gradient
flow equation downward. The associated complete set of tangent vectors is
also generated in the same manner. Molecular dynamics is then formulated a
s a constrained dynamical system\, where the equations of motion with Lagr
ange multipliers\, are solved by the second-order constraint-preserving s
ymmetric integrator. \n The algorithm is tested in the lambda phi^4 model
at finite density\, by choosing the thimbles associated with the classical
vacua for subcritical and supercritical values of chemical potential. For
the lattice size L=4\, we find that the residual sign factors are safely
included by reweighting and that the results of the number density are con
sistent with those obtained by the complex Langevin simulations.\n\nhttps:
//indico.gsi.de/event/2451/contributions/9191/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9191/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The critical surface of QCD in the heavy quark region
DTSTART;VALUE=DATE-TIME:20140221T083000Z
DTEND;VALUE=DATE-TIME:20140221T090000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9192@indico.gsi.de
DESCRIPTION:Speakers: Hana Saito (DESY\, NIC)\nWe apply the histogram meth
od to investigate the critical surface of QCD in the heavy quark region us
ing lattice QCD simulation. In this study\, we employ the reweighting tech
nique and cumulant expansion in order to analyze the quark masses dependen
ce of the critical surface and the quark chemical potential dependence. Fi
nally\, we show our results that a series of our methods works well to cla
rify the critical surface of the heavy quark region.\n\nhttps://indico.gsi
.de/event/2451/contributions/9192/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9192/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The density-of-states approach for dense matter Monte-Carlo simula
tions
DTSTART;VALUE=DATE-TIME:20140221T090000Z
DTEND;VALUE=DATE-TIME:20140221T093000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9193@indico.gsi.de
DESCRIPTION:Speakers: Kurt Langfeld (Plymouth University)\nDense matter qu
antum field theory is hampered by the notorious sign-problem: the Gibbs fa
ctor is not (semi-)positive definite and standard Monte-Carlo simulations
are not applicable. We propose to perform Monte-Carlo sampling with respec
t to the density of states\, which is positive even for dense matter syste
ms. I showcase this approach for a SU(2) gauge theory at finite densities
of heavy quarks. I then address the Z3 spin model at finite chemical poten
tials\, which features a strong sign problem.\n\nhttps://indico.gsi.de/eve
nt/2451/contributions/9193/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9193/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Subsets in QCD (II)
DTSTART;VALUE=DATE-TIME:20140220T154000Z
DTEND;VALUE=DATE-TIME:20140220T161000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9194@indico.gsi.de
DESCRIPTION:Speakers: Jacques Bloch (University of Regensburg)\nWe present
properties of Z3 subsets for QCD in two or more dimensions.\n\nhttps://in
dico.gsi.de/event/2451/contributions/9194/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9194/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nature of phase transitions in finite temperature and density QCD
with many-flavors
DTSTART;VALUE=DATE-TIME:20140221T080000Z
DTEND;VALUE=DATE-TIME:20140221T083000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9195@indico.gsi.de
DESCRIPTION:Speakers: Shinji Ejiri (Niigata University)\nWe investigate th
e phase structure of (2+Nf)-flavor QCD\, where two light flavors and Nf ma
ssive flavors exist\, to discuss the feasibility of the electroweak baryog
enesis in realistic technicolor scenario and to understand properties of f
inite density QCD. \nBecause an appearance of a first order phase transiti
on at finite temperature is a necessary condition for the baryogenesis\, i
t is important to study the nature of finite temperature phase transition.
\nApplying the reweighting method\, the probability distribution function
of the plaquette is calculated in the many-flavor QCD.\nThrough the shape
of the distribution function\, we determine the critical mass of heavy fla
vors terminating the first order region\, and find it to become larger wit
h Nf.\nWe then study the critical line at finite density and the first ord
er region is found to become wider as increasing the chemical potential. \
nWe discuss how the properties of real (2+1)-flavor QCD at finite temperat
ure and density can be understand from simulations of many-flavor QCD.\n\n
https://indico.gsi.de/event/2451/contributions/9195/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9195/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Langevin and Lefschetz
DTSTART;VALUE=DATE-TIME:20140220T140000Z
DTEND;VALUE=DATE-TIME:20140220T143000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9196@indico.gsi.de
DESCRIPTION:Speakers: Aarts ()\nhttps://indico.gsi.de/event/2451/contribut
ions/9196/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9196/
END:VEVENT
BEGIN:VEVENT
SUMMARY:EMMI
DTSTART;VALUE=DATE-TIME:20140219T150000Z
DTEND;VALUE=DATE-TIME:20140219T151500Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9197@indico.gsi.de
DESCRIPTION:Speakers: Carlo Ewerz (EMMI\, GSI Darmstadt)\nhttps://indico.g
si.de/event/2451/contributions/9197/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9197/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Langevin with meromorphic drift: problems and partial solutions
DTSTART;VALUE=DATE-TIME:20140220T090000Z
DTEND;VALUE=DATE-TIME:20140220T093000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9199@indico.gsi.de
DESCRIPTION:Speakers: Erhard Seiler (Max-Planck-Institut füir Physik)\nTh
e formal justification of the Langevin method for the solution of sign pro
blems does not allow singularities in the drift. This is a problem for QCD
at finite density where zeroes of the fermion determinant produce poles i
n the drift. We review briefly the\nmathematical origin of the problem and
describe various strategies to deal with it\, as well as their limitation
s.\n\nhttps://indico.gsi.de/event/2451/contributions/9199/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9199/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Complex Langevin for chiral Random Matrix Theory at nonzero chemic
al potential
DTSTART;VALUE=DATE-TIME:20140220T083000Z
DTEND;VALUE=DATE-TIME:20140220T090000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9200@indico.gsi.de
DESCRIPTION:Speakers: Kim Splittorff ()\nAbstract: Complex Langevin dynami
cs is the most appealing and challenging approach to solve the sign proble
m in QCD at nonzero chemical potential. We apply complex Langevin dynamics
to chiral random matrix theory. In the microscopic limit this random matr
ix theory is equivalent to QCD and the sign problem due to the complex val
ued fermion determinant is equally severe. We discuss how the Langevin for
ce is affected by the presence of the logarithm of the fermion determinant
in the action and test the complex Langevin simulations against the exact
analytic results for chiral random matrix theory.\n\nhttps://indico.gsi.d
e/event/2451/contributions/9200/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9200/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Simulating full QCD at nonzero density using the complex Langevin
equation
DTSTART;VALUE=DATE-TIME:20140220T080000Z
DTEND;VALUE=DATE-TIME:20140220T083000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9201@indico.gsi.de
DESCRIPTION:Speakers: Denes Sexty (Uni Heidelberg)\nThe complex Langevin m
ethod is extended to full QCD at non-zero chemical potential. The use of g
auge cooling stabilizes the simulations\nat small enough lattice spacings.
The method allows simulations also at high densities\, all the way up to
saturation. Results are compared to the reweighting approach.\n\nhttps://i
ndico.gsi.de/event/2451/contributions/9201/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9201/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Exploring the phase structure of Yang-Mills theories in the presen
ce of a theta term
DTSTART;VALUE=DATE-TIME:20140219T154500Z
DTEND;VALUE=DATE-TIME:20140219T161500Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9202@indico.gsi.de
DESCRIPTION:Speakers: Massimo D'Elia (University of Pisa and INFN)\nI disc
uss recent results regarding the phase structure non-Abelian gauge theorie
s in the presence of a topological theta term\, which are based on numeric
al simulations performed at imaginary values of theta.\n\nhttps://indico.g
si.de/event/2451/contributions/9202/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9202/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Theta dependence of 4D SU(N) gauge theories at finite temperature
DTSTART;VALUE=DATE-TIME:20140219T151500Z
DTEND;VALUE=DATE-TIME:20140219T154500Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9203@indico.gsi.de
DESCRIPTION:Speakers: ettore vicari (physics department\, university of Pi
sa)\nThe dependence of 4D SU(N) gauge theories on the topological theta\nt
erm is investigated at finite temperature\, and in particular in the\nlarg
e-N limit. General arguments and numerical analyses exploiting\nthe latti
ce formulation show that it drastically changes across the\ndeconfinement
transition. The low-T phase is characterized by a\nlarge-N scaling with t
heta/N as relevant variable\, while in the high-T\nphase the scaling varia
ble is just theta and the free energy is\nessentially determined by the in
stanton-gas approximation.\n\nhttps://indico.gsi.de/event/2451/contributio
ns/9203/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9203/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Taming the sign problem using tensor renormalization
DTSTART;VALUE=DATE-TIME:20140219T140000Z
DTEND;VALUE=DATE-TIME:20140219T143000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9204@indico.gsi.de
DESCRIPTION:Speakers: Yannick Meurice (University of Iowa)\nWe consider th
e sign problem for classical spin models at complex beta =1/g^2 on square
lattices. We show that the tensor renormalization group method allows rel
iable calculations for larger Im beta than the reweighting Monte Carlo met
hod. For the Ising model with complex beta we compare our results with the
exact Onsager-Kaufman solution at finite volume. We show that the Fisher
zeros can be determined precisely with the TRG method. We check the conver
gence of the TRG method for the O(2) model when the number of states incr
eases. We show that the finite size scaling of the calculated Fisher zeros
agrees very well with the Kosterlitz-Thouless transition assumption and p
redicts the locations for larger volume. \nWe present new applications o
f the TRG method for the O(2) model with a chemical potential. It provides
robust estimations of the eigenvalues of the transfer matrix. The results
are in good agreement with results obtained with the worm algorithm devel
oped by Banerjee and Chandrasekharan.\nWe discuss the phase diagram in the
beta-mu plane. We discuss the possibility of using this framework to desc
ribe real time evolution.\n\nhttps://indico.gsi.de/event/2451/contribution
s/9204/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9204/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Isospin chemical potential and magnetic fields
DTSTART;VALUE=DATE-TIME:20140219T133000Z
DTEND;VALUE=DATE-TIME:20140219T140000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9205@indico.gsi.de
DESCRIPTION:Speakers: Gergely Endrodi ()\nThe pion condensation phase of Q
CD at large isospin chemical potential is studied in the presence of an ex
ternal magnetic field. Since the up and down quark electric charges differ
\, the external field induces a sign problem\, which is circumvented throu
gh a Taylor-expansion method.\n\nhttps://indico.gsi.de/event/2451/contribu
tions/9205/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9205/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nonzero isospin density
DTSTART;VALUE=DATE-TIME:20140219T130000Z
DTEND;VALUE=DATE-TIME:20140219T133000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9206@indico.gsi.de
DESCRIPTION:Speakers: Detmold ()\nhttps://indico.gsi.de/event/2451/contrib
utions/9206/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9206/
END:VEVENT
BEGIN:VEVENT
SUMMARY:New tools for characterizing Lattice gauge theories\, tensor netwo
rks and quantum simulators
DTSTART;VALUE=DATE-TIME:20140221T133000Z
DTEND;VALUE=DATE-TIME:20140221T140000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9207@indico.gsi.de
DESCRIPTION:Speakers: Taggliacozzo ()\nAfter a short introduction about te
nsor networks and quantum simulators\, I will review the recent proposals
on how to apply both of them to the characterization of Abelian and non-Ab
elian lattice gauge theories.\n\nhttps://indico.gsi.de/event/2451/contribu
tions/9207/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9207/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Atomic Quantum Simulation of Abelian and non-Abelian Gauge Theorie
s
DTSTART;VALUE=DATE-TIME:20140221T130000Z
DTEND;VALUE=DATE-TIME:20140221T133000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9208@indico.gsi.de
DESCRIPTION:Speakers: Uwe-Jens Wiese (Bern University)\nGauge theories pla
y an important role both in particle and condensed matter physics\, with a
pplications ranging from QCD to spin liquids\, and Kitaev's toric code in
quantum information theory. Numerical simulations of such systems on class
ical computers suffer from very severe sign problems. Quantum simulators a
re accurately controllable quantum systems that can mimic other quantum sy
stems. They do not suffer from sign problems\, because their hardware is i
ntrinsically quantum mechanical. Recently\, using \nultracold atoms in opt
ical lattices\, quantum simulators have been designed for Abelian and non-
Abelian gauge theories. Their experimental realization is a challenge for
the foreseeable future\, which holds the promise to access physical phenom
ena\, as\, for example\, the evolution of strongly coupled quantum systems
in real time\, whose understanding has remained beyond reach of the tradi
tional tools of theoretical physics.\n\nhttps://indico.gsi.de/event/2451/c
ontributions/9208/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9208/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Worldline approach to lattice QCD at finite coupling
DTSTART;VALUE=DATE-TIME:20140221T150000Z
DTEND;VALUE=DATE-TIME:20140221T153000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9209@indico.gsi.de
DESCRIPTION:Speakers: Helvio Vairinhos (University of Porto)\nWe explore t
he possibility of describing lattice QCD in the worldline approach beyond
strong coupling. We construct MDP models of lattice gauge theories with st
aggered fermions for arbitrary values of the lattice coupling\, by integra
ting out all the link variables exactly. We discuss the implications of ou
r constructions to the sign problem at finite coupling and density.\n\nhtt
ps://indico.gsi.de/event/2451/contributions/9209/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9209/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Real-time dynamics without Hamiltonians
DTSTART;VALUE=DATE-TIME:20140221T140000Z
DTEND;VALUE=DATE-TIME:20140221T143000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9210@indico.gsi.de
DESCRIPTION:Speakers: Debasish Banerjee (Albert Einstein Center\, Universi
ty of Bern)\nSimulating real-time dynamics of large quantum systems is a n
otoriously difficult problem. Diagonalizing the Hamiltonian is exponential
ly expensive\, while the configurations contribute a complex weight to the
real-time path integral leading to a severe sign-problem. In this particu
lar case\, we consider a system of spins whose dynamics is driven by measu
rements of nearest neighbor spin pair. Remarkably\, averaging over the mea
surement results lead to a sign-problem free real-time path integral which
can be simulated with an efficient cluster algorithm.\n\nhttps://indico.g
si.de/event/2451/contributions/9210/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9210/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Pierre van Baal
DTSTART;VALUE=DATE-TIME:20140220T150000Z
DTEND;VALUE=DATE-TIME:20140220T151000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9211@indico.gsi.de
DESCRIPTION:Speakers: Jacobus Verbaarschot Verbaarschot (Stony Brook Unive
rsity)\nhttps://indico.gsi.de/event/2451/contributions/9211/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9211/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Complex saddle points in QCD at finite density
DTSTART;VALUE=DATE-TIME:20140221T153000Z
DTEND;VALUE=DATE-TIME:20140221T160000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9212@indico.gsi.de
DESCRIPTION:Speakers: Hiromichi Nishimura (University of Bielefeld)\nWe co
nsider complex saddle points in finite-density QCD\, which are constrained
by charge and complex conjugations to make the effective action real. Th
e method naturally incorporates color neutrality\, and the Polyakov loop a
nd the conjugate loop at the saddle point are real but not identical. More
over\, it gives rise to a complex mass matrix associated with Polyakov loo
ps\, reflecting oscillatory behavior in color-charge densities. These resu
lts may be experimentally relevant at GSI/FAIR.\n\nhttps://indico.gsi.de/e
vent/2451/contributions/9212/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9212/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Complex Langevin dynamics for SU(3) gauge theory with a theta term
DTSTART;VALUE=DATE-TIME:20140220T103000Z
DTEND;VALUE=DATE-TIME:20140220T110000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9213@indico.gsi.de
DESCRIPTION:Speakers: Bongiovanni ()\nhttps://indico.gsi.de/event/2451/con
tributions/9213/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9213/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Approaching finite density QCD using Complex Langevin Simulation
DTSTART;VALUE=DATE-TIME:20140220T100000Z
DTEND;VALUE=DATE-TIME:20140220T103000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9214@indico.gsi.de
DESCRIPTION:Speakers: Ion-Olimpiu Stamatescu (Univ. Heuidelberg)\nWe study
the various aspects of the method on simple\, soluble cases used as effec
tive models\, then extend the analysis to more complex lattice models with
non-trivial phase structure. We finally apply the method to study HQCD\,
a full QCD-approximation for heavy quarks which allows putting questions o
f direct physical interest.\n\nhttps://indico.gsi.de/event/2451/contributi
ons/9214/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9214/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dual variables approach to finite density lattice field theories
DTSTART;VALUE=DATE-TIME:20140218T130000Z
DTEND;VALUE=DATE-TIME:20140218T133000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9215@indico.gsi.de
DESCRIPTION:Speakers: Christof Gattringer (Universität Graz)\nI give an o
verview of recent results for using dual variables in lattice field theori
es at finite density. I review systems where the complex action problem wa
s solved with dual variables and discuss the role of these reference model
s for assessing other approaches to finite density.\n\nhttps://indico.gsi.
de/event/2451/contributions/9215/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9215/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Conserved charge fluctuations and the QCD phase diagram
DTSTART;VALUE=DATE-TIME:20140218T090000Z
DTEND;VALUE=DATE-TIME:20140218T093000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9217@indico.gsi.de
DESCRIPTION:Speakers: Christian Schmidt (Universitaet Bielefeld)\nWe will
review recent progress on the calculation of conserved\ncharge fluctuation
s with highly improved staggered quarks (HISQ).\nIn particular we will foc
us on higher order cumulants of net baryon\nnumber\, net electric charge a
nd net strangeness fluctuations. We will discuss how these quantities appr
oach the hadron resonance gas model at low temperatures and analyze to
what extent they show sensitivity to\nuniversal scaling behavior\, i.e. we
estimate the relative strength of\ncontributions from the regular and sin
gular part of the free energy.\nBased on this analysis we discuss conseque
nces for the convergence\nradius of the Taylor expansion of the pressure a
nd possible\nexperimental observables of the QCD critical point.\n\nhttps:
//indico.gsi.de/event/2451/contributions/9217/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9217/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Fluctuations of conserved charges
DTSTART;VALUE=DATE-TIME:20140218T083000Z
DTEND;VALUE=DATE-TIME:20140218T090000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9218@indico.gsi.de
DESCRIPTION:Speakers: Stefan Krieg (Forschungszentrum Juelich GmbH)\nI wil
l review recent results on fluctuations of conserved charges at finite tem
perature and discuss how they can be used to estimate the temperature and
chemical potential at the time of chemical freeze-out.\n\nhttps://indico.g
si.de/event/2451/contributions/9218/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9218/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Fluctuations of strangeness and charm from Lattice QCD
DTSTART;VALUE=DATE-TIME:20140218T103000Z
DTEND;VALUE=DATE-TIME:20140218T110000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9219@indico.gsi.de
DESCRIPTION:Speakers: Sayantan Sharma ()\nhttps://indico.gsi.de/event/2451
/contributions/9219/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9219/
END:VEVENT
BEGIN:VEVENT
SUMMARY:QCD at imaginary chemical potential with Wilson fermions
DTSTART;VALUE=DATE-TIME:20140218T100000Z
DTEND;VALUE=DATE-TIME:20140218T103000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9220@indico.gsi.de
DESCRIPTION:Speakers: Andrei Alexandru ()\nWe investigate the phase diagra
m in the temperature\, imaginary chemical potential plane for Nf=3 QCD usi
ng Wilson type fermions. While more expensive than the staggered fermions
used in past studies in this area\, Wilson fermions can be used safely to
simulate systems with three quark flavors. In this talk\, we focus on the
(pseudo)critical line that extends from mu=0 in the imaginary chemical pot
ential plane\, trace it to the Roberge-Weiss line\, and determine its loca
tion relative to the Roberge-Weiss transition point. Our results are compa
tible with the standard expectations.\n\nhttps://indico.gsi.de/event/2451/
contributions/9220/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9220/
END:VEVENT
BEGIN:VEVENT
SUMMARY:QCD with one flavor and the sign problem at fixed theta-angle
DTSTART;VALUE=DATE-TIME:20140221T100000Z
DTEND;VALUE=DATE-TIME:20140221T103000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9221@indico.gsi.de
DESCRIPTION:Speakers: Jacobus Verbaarschot Verbaarschot (Stony Brook Unive
rsity)\nRandom matrix theory has had a significant impact on our understan
ding\nof the sign problem and nonzero baryon chemical potential. Among oth
ers\nit has explained the nature of the quenched approximation\, the relat
ion\nbetween Dirac spectra and the sign problem\, the Silver Blaze problem
and \nthe microscopic Dirac spectrum. Perhaps the most surprising result
from\nrandom matrix theory is that the discontinuity of the chiral condens
ate\nrequires an alternative of the Banks-Casher formula. This mechanism o
ccurs\nboth in random matrix theory and one-dimensional QCD and in this le
cture\nwe discuss the universality of this mechanism for chiral symmetry b
reaking.\nRelations with the sign problem at nonzero $\\theta$-angle are d
iscussed.\n\nhttps://indico.gsi.de/event/2451/contributions/9221/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9221/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Opening
DTSTART;VALUE=DATE-TIME:20140218T081500Z
DTEND;VALUE=DATE-TIME:20140218T083000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9222@indico.gsi.de
DESCRIPTION:https://indico.gsi.de/event/2451/contributions/9222/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9222/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Registration
DTSTART;VALUE=DATE-TIME:20140218T073000Z
DTEND;VALUE=DATE-TIME:20140218T081500Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9223@indico.gsi.de
DESCRIPTION:https://indico.gsi.de/event/2451/contributions/9223/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9223/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Surprising phase structures for Wilson and twisted mass fermions
DTSTART;VALUE=DATE-TIME:20140221T103000Z
DTEND;VALUE=DATE-TIME:20140221T110000Z
DTSTAMP;VALUE=DATE-TIME:20240914T105615Z
UID:indico-contribution-2451-9224@indico.gsi.de
DESCRIPTION:Speakers: Mario Kieburg (Universität Bielefeld)\nThe existenc
e of the Aoki phase is one of the new structures of the phase space in lat
tice QCD when introducing Wilson fermions. It is expected that the Aoki ph
ase may have also an impact on Wilson fermions at finite chemical potentia
l. I am going to present new results on these phase space structures for W
ilson fermions in a two-flavor theory with a finite real as well as imagin
ary iso-spin chemical potential. These new structures are manifested in th
e lowest eigenvalues of the Dirac operator. I am going to point out what t
he order parameters of these new phases are and to answer the question on
the analytic continuation of the chemical potential. Since the Wilson Dira
c operator at finite iso-spin chemical potential is unitarily equivalent t
o the twisted mass Dirac operator for two flavors\, the spectrum and\, hen
ce\, the phase diagram applies to this kind of fermions\, too.\n\nhttps://
indico.gsi.de/event/2451/contributions/9224/
LOCATION:GSI KBW Lecture Hall
URL:https://indico.gsi.de/event/2451/contributions/9224/
END:VEVENT
END:VCALENDAR