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SUMMARY:Structure of the Lefschetz thimbles decomposition of lattice fermi
on models
DTSTART;VALUE=DATE-TIME:20201111T160000Z
DTEND;VALUE=DATE-TIME:20201111T163000Z
DTSTAMP;VALUE=DATE-TIME:20230922T144317Z
UID:indico-contribution-21-252@indico.ihep.su
DESCRIPTION:Speakers: Maksim Ulybyshev ()\nWe discuss a framework for stu
dying the properties of the Lefschetz\nthimbles decomposition for lattice
fermion models. Non-iterative\nsolver for the inversion of fermion determi
nants forms the core of the\nmethod. It allows us to solve the gradient fl
ow (GF) equations taking\ninto account the fermion determinant exactly. Be
ing able to do so\, we\ncan find both real and complex saddle points of th
e lattice action and\ndescribe the structure of the Lefschetz thimbles dec
omposition for\nlarge enough lattices to extrapolate our results to the th
ermodynamic\nlimit.\nWe show two possible applications of this technique.
First of all\, the\nknowledge about the saddle points can help us to simpl
ify the\nstructure of the Lefschetz thimbles decomposition and to alleviat
e the\nsign problem. The second application is systematic building of the\
nquasi-classical approximation taking into account Gaussian\nfluctuations
around exact saddle points.\n\nhttps://indico.ihep.su/event/563/contributi
ons/252/
LOCATION:
URL:https://indico.ihep.su/event/563/contributions/252/
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BEGIN:VEVENT
SUMMARY:Universality driven analytic structure of QCD crossover
DTSTART;VALUE=DATE-TIME:20201111T153000Z
DTEND;VALUE=DATE-TIME:20201111T160000Z
DTSTAMP;VALUE=DATE-TIME:20230922T144317Z
UID:indico-contribution-21-232@indico.ihep.su
DESCRIPTION:Speakers: Vladimir Skokov (North Carolina State University / R
BRC BNL)\, Gregory Johnson ()\nRecent lattice QCD calculations show strong
indications that the chiral crossover of QCD at zero baryon chemical pote
ntial \\mu_B is a remnant of the second-order chiral phase transition. Fur
thermore\, the non-universal parameters needed to map temperature T and \\
mu_B to the universal properties of the second-order chiral phase transiti
on have been determined recently. Motivated by these observations\, first\
, we determine the analytic structure of the partition function -- the so-
called Yang-Lee edge singularity -- in the QCD crossover regime\, solely b
ased on universal properties. Next\, utilizing the lattice QCD results for
non-universal parameters we map this singularity to the real T and comple
x \\mu_B plane\, leading to the determination of the radius of convergence
in \\mu_B in the QCD crossover regime. These universality- and QCD-based
results provide tight constraints on the range of validity of the lattice
QCD calculations at \\mu_B>0. The implication of this result on the locati
on of the conjectured QCD critical point is discussed.\n\nhttps://indico.i
hep.su/event/563/contributions/232/
LOCATION:
URL:https://indico.ihep.su/event/563/contributions/232/
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SUMMARY:QCD phase diagram at non-zero real and imaginary chemical potentia
l from lattice QCD
DTSTART;VALUE=DATE-TIME:20201111T143000Z
DTEND;VALUE=DATE-TIME:20201111T150000Z
DTSTAMP;VALUE=DATE-TIME:20230922T144317Z
UID:indico-contribution-21-276@indico.ihep.su
DESCRIPTION:Speakers: Jishnu Goswami ()\nWe will show the continuum extra
polated results for all second order and some of the fourth order cumulant
s of net baryon-number\, strangeness and electric charge fluctuations as w
ell as their correlations obtained using the Highly Improved Staggered Qua
rk (HISQ) action in (2+1)-flavour QCD by the HotQCD collaboration. We will
show comparisons of our results with hadron resonance gas (HRG) model ca
lculations and argue that the HRG model based description of strongly inte
racting matter works only upto the pseudo-crtical temperature of QCD. The
cumulants of net charge fluctuations and their correlations at vanishing v
alues of the charge chemical potentials ($\\mu_{B\,Q\,S}=0$) provide the b
asis for Taylor expansions of various thermodynamic observables at non-zer
o values of the chemical potentials. We will use the updated results of Ho
tQCD on higher order cumulants to constrain the location of a possible cri
tical point in the QCD phase diagram.\n\n We will also show a calculation
of (2+1)-flavor QCD with an imaginary chemical potential with the aim to d
etermine the critical quark mass at which the second order transition in t
he Roberge-Weiss plane turns into a first order transition. We use the Hig
hly Improved Staggered Quark (HISQ) action and perform calculations in the
Roberge-Weiss plane\, where the value of the critical mass is expected to
be largest. We explore a range of quark masses corresponding to pion mass
values\, $m_{\\pi}$≥ 40 MeV. Contrary to calculations performed with un
improved actions we find no evidence for the occurrence of first order tra
nsitions at the small quark mass values explored so far.\n \n\nOpen Proble
ms/discussions:\ni) Resummation of Taylor series at small value of the non
-zero baryon density?\nii) Interplay between RW transition and Chiral tran
sition in the Chiral limit?\n\nRef: arXiv:2011.02812 [hep-lat]\n\nhttps://
indico.ihep.su/event/563/contributions/276/
LOCATION:
URL:https://indico.ihep.su/event/563/contributions/276/
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BEGIN:VEVENT
SUMMARY:QCD crossover line at finite chemical potential from the Lattice
DTSTART;VALUE=DATE-TIME:20201111T150000Z
DTEND;VALUE=DATE-TIME:20201111T153000Z
DTSTAMP;VALUE=DATE-TIME:20230922T144317Z
UID:indico-contribution-21-224@indico.ihep.su
DESCRIPTION:Speakers: Jana Guenther (University of Regensburg)\nQCD crosso
ver line at finite chemical potential from the Lattice\nAn efficient way t
o study the QCD phase diagram at small finite density\nis to extrapolate t
hermodynamical observables from imaginary chemical potential.\nThe phase d
iagram features a crossover line starting from the\ntransition temperature
already determined at zero chemical potential.\nThis talk focuses on the
Taylor expansion of this line up to $\\mu^4$ contributions. We present\nth
e continuum extrapolation of the crossover temperature.\n\nhttps://indico.
ihep.su/event/563/contributions/224/
LOCATION:
URL:https://indico.ihep.su/event/563/contributions/224/
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SUMMARY:QCD Phase Diagrams with Charge and Isospin Axes under Heavy-Ion Co
llision and Stellar Conditions
DTSTART;VALUE=DATE-TIME:20201111T140000Z
DTEND;VALUE=DATE-TIME:20201111T143000Z
DTSTAMP;VALUE=DATE-TIME:20230922T144317Z
UID:indico-contribution-21-209@indico.ihep.su
DESCRIPTION:Speakers: Veronica Dexheimer (Kent State University)\nWe inves
tigate the phase transition from hadron to quark matter in the general cas
e without the\nassumption of chemical equilibrium. The effects of net stra
ngeness on charge and isospin fractions\,\nchemical potentials\, and tempe
rature are studied in the context of the Chiral Mean Field (CMF)\nmodel th
at incorporates chiral symmetry restoration and deconfinement. The extent
to which\nthese quantities are probed during deconfinement in conditions e
xpected to exist in protoneutron\nstars\, binary neutron-star mergers\, an
d heavy-ion collisions is analyzed via the construction of 3-\ndimensional
phase diagrams.\n\nhttps://indico.ihep.su/event/563/contributions/209/
LOCATION:
URL:https://indico.ihep.su/event/563/contributions/209/
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SUMMARY:The high density QCD phase diagram: of heavy ion collisions and ne
utron star mergers
DTSTART;VALUE=DATE-TIME:20201111T133000Z
DTEND;VALUE=DATE-TIME:20201111T140000Z
DTSTAMP;VALUE=DATE-TIME:20230922T144317Z
UID:indico-contribution-21-228@indico.ihep.su
DESCRIPTION:Speakers: Jan Steinheimer (Frankfurt Institute for Advanced St
udies)\nI will discuss the limits of current methods to calculate the equa
tion of state of QCD matter at finite baryon density. All methods based on
expanding lattice QCD results show to be limitred to $\\mu_B/T<3$ a regio
n where contributions from the net baryon density are negligible. Therefor
e I will show how it is possible to use constraints from astrophysical obs
ervations of neutron stars and their mergers\, as well as observables from
heavy ion collisions\, to constrain the features of the QCD EoS at densit
ies up to 10 times nuclear saturation density and Temperatures up to 200 M
eV.\n\nhttps://indico.ihep.su/event/563/contributions/228/
LOCATION:
URL:https://indico.ihep.su/event/563/contributions/228/
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BEGIN:VEVENT
SUMMARY:On the phase structure of QCD
DTSTART;VALUE=DATE-TIME:20201111T130000Z
DTEND;VALUE=DATE-TIME:20201111T133000Z
DTSTAMP;VALUE=DATE-TIME:20230922T144317Z
UID:indico-contribution-21-249@indico.ihep.su
DESCRIPTION:Speakers: Jan M. Pawlowski (Heidelberg University)\nWe map out
the QCD phase structure with functional approaches. By now the results fo
r the phase structure from these approaches also converge at large densiti
es\, including the location of the critical end point. We evaluate the rem
aining systematic errors and tasks\, as well the the prospects.\n\nhttps:/
/indico.ihep.su/event/563/contributions/249/
LOCATION:
URL:https://indico.ihep.su/event/563/contributions/249/
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