7,592 research outputs found
Equilibrium Thermodynamics of Lattice QCD
Lattice QCD allows us to simulate QCD at non-zero temperature and/or
densities. Such equilibrium thermodynamics calculations are relevant to the
physics of relativistic heavy-ion collisions. I give a brief review of the
field with emphasis on our work.Comment: 15 pages, 9 figures. Talk presented at SCGT06, Nagoya, Japan. Version
2 includes minor modifications to reference work not covered in version
Quantization and simulation of Born-Infeld non-linear electrodynamics on a lattice
Born-Infeld non-linear electrodynamics arises naturally as a field theory
description of the dynamics of strings and branes. Most analyses of this theory
have been limited to studying it as a classical field theory. We quantize this
theory on a Euclidean 4-dimensional space-time lattice and determine its
properties using Monte-Carlo simulations. The electromagnetic field around a
static point charge is measured using Luscher-Weisz methods to overcome the
sign problem associated with the introduction of this charge. The D field
appears identical to that of Maxwell QED. However, the E field is enhanced by
quantum fluctuations, while still showing the short distance screening observed
in the classical theory. In addition, whereas for the classical theory, the
screening increases without bound as the non-linearity increases, the quantum
theory approaches a limiting conformal field theory.Comment: 24 pages, 10 figures. Latex with postscript figure
Complex Langevin Simulations of QCD at Finite Density -- Progress Report
We simulate lattice QCD at finite quark-number chemical potential to study
nuclear matter, using the complex Langevin equation (CLE). The CLE is used
because the fermion determinant is complex so that standard methods relying on
importance sampling fail. Adaptive methods and gauge-cooling are used to
prevent runaway solutions. Even then, the CLE is not guaranteed to give correct
results. We are therefore performing extensive testing to determine under what,
if any, conditions we can achieve reliable results. Our earlier simulations at
, on a lattice reproduced the expected phase
structure but failed in the details. Our current simulations at on
a lattice fail in similar ways while showing some improvement. We are
therefore moving to even weaker couplings to see if the CLE might produce the
correct results in the continuum (weak-coupling) limit, or, if it still fails,
whether it might reproduce the results of the phase-quenched theory. We also
discuss action (and other dynamics) modifications which might improve the
performance of the CLE.Comment: Talk presented at Lattice 2017, Granada, Spain and submitted to
proceedings. 8 pages, 4 figure
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