Chiral and deconfinement transitions in strong coupling lattice QCD with finite coupling and Polyakov loop effects

TL;DR

This paper explores how Polyakov loop effects influence chiral and deconfinement transitions in strong coupling lattice QCD, revealing their impact on transition temperatures and the nature of the transitions.

Contribution

It introduces a comprehensive analysis of Polyakov loop effects in strong coupling lattice QCD, comparing approximation schemes and clarifying their influence on phase transitions.

Findings

Polyakov loop suppresses chiral condensate.

Reduces chiral transition temperature, aligning with Monte Carlo results.

Deconfinement transition is crossover for light quarks and first order for heavy quarks.

Abstract

We investigate chiral and deconfinement transitions in the framework of the strong coupling lattice QCD for color SU(3) with one species of unrooted staggered fermion at finite temperature and quark chemical potential. We take account of the leading order Polyakov loop terms as well as the next-to-next-to-leading order (1/g^4) fermionic terms of the strong coupling expansion in the effective action. We investigate the Polyakov loop effects by comparing two approximation schemes, a Haar measure method (no fluctuation from the mean field) and a Weiss mean-field method (with fluctuations). The effective potential is obtained in both cases, and we analytically clarify the Polyakov loop contributions to the effective potential. The Polyakov loop is found to suppress the chiral condensate and to reduce the chiral transition temperature at mu=0, and the chiral transition temperature roughly reproduces the Monte Carlo results at beta=2N_c/g^2 \lesssim 4. The deconfinement transition is found to be the crossover and first order for light (am_0 \lesssim 4 at beta=4) and heavy quark masses, respectively.