5,184 research outputs found
Block Spin Effective Action for Polyakov Loops in 4D SU(2) LGT
Using a variant of the IMCRG method of Gupta and Cordery, we explicitly
compute majority rule block spin effective actions for the signs of the
Polyakov loops in 4D SU(2) finite temperature lattice gauge theories. To the
best of our knowledge, this is the first attempt to compute numerically
effective actions for the Polyakov loop degrees of freedom in 4D SU(2). The
most important observations are: 1. The renormalization group flow at the
deconfinement transition can be nicely matched with the flow of the 3D Ising
model, thus confirming the Svetitsky-Yaffe conjecture. 2. The IMCRG simulations
of the FT SU(2) model have strongly reduced critical slowing down.Comment: Contribution to the Lattice 97 proceedings, LaTeX, 3 pages, 3
figures, uses espcrc2.sty, epsfig.st
Non-perturbative determination of anisotropy coefficients in lattice gauge theories
We propose a new non-perturbative method to compute derivatives of gauge
coupling constants with respect to anisotropic lattice spacings (anisotropy
coefficients), which are required in an evaluation of thermodynamic quantities
from numerical simulations on the lattice. Our method is based on a precise
measurement of the finite temperature deconfining transition curve in the
lattice coupling parameter space extended to anisotropic lattices by applying
the spectral density method. We test the method for the cases of SU(2) and
SU(3) gauge theories at the deconfining transition point on lattices with the
lattice size in the time direction -- 6. In both cases, there is a
clear discrepancy between our results and perturbative values. A longstanding
problem, when one uses the perturbative anisotropy coefficients, is a
non-vanishing pressure gap at the deconfining transition point in the SU(3)
gauge theory. Using our non-perturbative anisotropy coefficients, we find that
this problem is completely resolved: we obtain and
on and 6 lattices, respectively.Comment: 24pages,7figures,5table
Non-perturbative determination of anisotropy coefficients and pressure gap at the deconfining transition of QCD
We propose a new non-perturbative method to compute derivatives of gauge
coupling constants with respect to anisotropic lattice spacings (anisotropy
coefficients). Our method is based on a precise measurement of the finite
temperature deconfining transition curve in the lattice coupling parameter
space extended to anisotropic lattices by applying the spectral density method.
We determine the anisotropy coefficients for the cases of SU(2) and SU(3) gauge
theories. A longstanding problem, when one uses the perturbative anisotropy
coefficients, is a non-vanishing pressure gap at the deconfining transition
point in the SU(3) gauge theory. Using our non-perturbative anisotropy
coefficients, we find that this problem is completely resolved.Comment: LATTICE98(hightemp
Book review: Handbook of the Media in Asia
Gunaratne, Shelton (ed) (2000) Handbook of the Media in Asia, Sage Publications, New Delhi, 722 pp. ISBN 0-7619-9427-0
Reviewed by Kevin Engels
To describe this book as a âHandbookâ is an understatement. It is a comprehensive survey and outline of the media throughout 25 countries of Asia, from Pakistan in the West to Mongolia in the Northeast and the Philippines in the Southeast. Not only are the major nations and economies covered but countries such as Maldives and Macau are included
Scaling Properties of the Energy Density in SU(2) Lattice Gauge Theory
The lattice data for the energy density of gauge theory are
calculated with \nop~derivatives of the coupling constants. These derivatives
are obtained from two sources : i) a parametrization of the \nop~beta function
in accord with the measured critical temperature and values and
ii) a \nop~calculation of the presssure. We then perform a detailed finite size
scaling analysis of the energy density near . It is shown that at the
critical temperature the energy density is scaling as a function of with
the corresponding Ising model critical exponents. The value of
in the continuum limit is estimated to be 0.256(23). In
the high temperature regime the energy density is approaching its weak coupling
limit from below, at it has reached only about of the
limit.Comment: 15 pages + 9 figures, BI-TP 94/3
On a possibility of adjoint colored states condensation at finite temperatures in lattice gauge model
Cooled down and diluted quark-gluon matter is considered. A possibility of
condensation of multiquark clusters with zero N-alities is discussed.Comment: Lattice99:Finite Temperature and Density sessio
Critical behaviour and scaling functions of the three-dimensional O(6) model
We numerically investigate the three-dimensional O(6) model on 12^3 to 120^3
lattices within the critical region at zero magnetic field, as well as at
finite magnetic field on the critical isotherm and for several fixed couplings
in the broken and the symmetric phase. We obtain from the Binder cumulant at
vanishing magnetic field the critical coupling J_c=1.42865(3). The universal
value of the Binder cumulant at this point is g_r(J_c)=-1.94456(10). At the
critical coupling, the critical exponents \gamma=1.604(6), \beta=0.425(2) and
\nu=0.818(5) are determined from a finite-size-scaling analysis. Furthermore,
we verify predicted effects induced by massless Goldstone modes in the broken
phase. The results are well described by the perturbative form of the model's
equation of state. Our O(6)-result is compared to the corresponding Ising, O(2)
and O(4) scaling functions. Finally, we study the finite-size-scaling behaviour
of the magnetisation on the pseudocritical line.Comment: 13 pages, 20 figures, REVTEX, fixed an error in the determination of
R_\chi and changed the corresponding line in figure 13
Finite temperature QCD
Engels J. Finite temperature QCD. In: Bleuler K, ed. Quarks and Nuclear Structure: Proceedings of the 3rd Klaus Erkelenz Symposium held at Bad Honnef, June 13â16,1983. Lecture Notes in Physics, 197. Berlin [u.a.]: Springer; 1984: 39-56.A review of finite temperature lattice calculations for quantum chromodynamics is given. We show how the thermodynamic quantities can be evaluated by Monte Carlo methods, once finite temperature field theory has been formulated on a lattice. The existing results for chemical potential zero and in quenched approximation are discussed. They exhibit a clear first order transition for SU(3) lattice QCD and probably a second order transition for SU(2) lattice QCD. The chiral and deconfinement transitions are coinciding in the quenched approximation
Critical behavior of 3D SU(2) gauge theory at finite temperature: exact results from universality
We show that universality arguments, namely the Svetitsky-Yaffe conjecture,
allow one to obtain exact results on the critical behavior of 3D SU(2) gauge
theory at the finite temperature deconfinement transition,through a mapping
into the 2D Ising model. In particular, we consider the finite-size scaling
behavior of the plaquette operator, which can be mapped into the energy
operator of the 2D Ising model. We obtain exact predictions for the dependence
of the plaquette expectation value on the size and shape of the lattice and we
compare them to Monte Carlo results, finding complete agreement. We discuss the
application of this method to the computation of more general correlators of
the plaquette operator at criticality, and its relevance to the study of the
color flux tube structure.Comment: 10 pages, LaTeX file + 3 eps figure
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