Numerical Calculation of Schwinger-Dyson Equation with Momentum-Dependent Gauge Parameter at Finite Temperature

Chiral symmetry at finite temperature is studied using the Schwinger-Dyson equation. We calculate numerically the critical temperature using the Schwinger-Dyson equation with the gauge parameter that depends on an external momentum. The critical temperature obtained by this method is similar to that with the Landau gauge and wave function renormalization constant 1. Moreover, the gauge invariance in the ladder approximation is examined using our method.Comment: 15 page, 12 figure

Quark spectral properties above Tc from Dyson-Schwinger equations

We report on an analysis of the quark spectral representation at finite temperatures based on the quark propagator determined from its Dyson-Schwinger equation in Landau gauge. In Euclidean space we achieve nice agreement with recent results from quenched lattice QCD. We find different analytical properties of the quark propagator below and above the deconfinement transition. Using a variety of ansaetze for the spectral function we then analyze the possible quasiparticle spectrum, in particular its quark mass and momentum dependence in the high temperature phase. This analysis is completed by an application of the Maximum Entropy Method, in principle allowing for any positive semi-definite spectral function. Our results motivate a more direct determination of the spectral function in the framework of Dyson-Schwinger equations

Spontaneous Scale Symmetry Breaking in 2+1-Dimensional QED at Both Zero and Finite Temperature

A complete analysis of dynamical scale symmetry breaking in 2+1-dimensional QED at both zero and finite temperature is presented by looking at solutions to the Schwinger-Dyson equation. In different kinetic energy regimes we use various numerical and analytic techniques (including an expansion in large flavour number). It is confirmed that, contrary to the case of 3+1 dimensions, there is no dynamical scale symmetry breaking at zero temperature, despite the fact that chiral symmetry breaking can occur dynamically. At finite temperature, such breaking of scale symmetry may take place.Comment: 12 pages, no figures, uses RevTeX4-bet

Chiral and deconfinement transition from correlation functions: SU(2) vs. SU(3)

We study a gauge invariant order parameter for deconfinement and the chiral condensate in SU(2) and SU(3) Yang-Mills theory in the vicinity of the deconfinement phase transition using the Landau gauge quark and gluon propagators. We determine the gluon propagator from lattice calculations and the quark propagator from its Dyson-Schwinger equation, using the gluon propagator as input. The critical temperature and a deconfinement order parameter are extracted from the gluon propagator and from the dependency of the quark propagator on the temporal boundary conditions. The chiral transition is determined using the quark condensate as order parameter. We investigate whether and how a difference in the chiral and deconfinement transition between SU(2) and SU(3) is manifest.Comment: 15 pages, 9 figures. For clarification one paragraph and two references added in the introduction and two sentences at the end of the first and last paragraph of the summary. Appeared in EPJ

High-Temperature Limit of Landau-Gauge Yang-Mills Theory

The infrared properties of the high-temperature limit of Landau-gauge Yang-Mills theory are investigated. In a first step the high-temperature limit of the Dyson-Schwinger equations is taken. The resulting equations are identical to the Dyson-Schwinger equations of the dimensionally reduced theory, a three-dimensional Yang-Mills theory coupled to an effective adjoint Higgs field. These equations are solved analytically in the infrared and ultraviolet, and numerically for all Euclidean momenta. We find infrared enhancement for the Faddeev-Popov ghosts, infrared suppression for transverse gluons and a mass for the Higgs. These results imply long-range interactions and over-screening in the chromomagnetic sector of high temperature Yang-Mills theory while in the chromoelectric sector only screening is observed.Comment: 21 pages, 23 figures, 3 tables, submitted to EPJ