The effect of the Polyakov loop on the chiral phase transition

TL;DR

This paper investigates how the Polyakov loop influences the chiral phase transition in a quark-meson model at finite temperature and chemical potential, using a resummation approach to analyze phase diagram features.

Contribution

It introduces a method to incorporate the Polyakov loop into the quark-meson model and studies its effect on the phase transition and critical points.

Findings

Polyakov loop impacts the location of the critical point.

Resummation method captures infinite orders in 1/N_f expansion.

Phase diagram features depend on the form of the Polyakov potential.

Abstract

The Polyakov loop is included in the SU(2)_L x SU(2)_R chiral quark-meson model by considering the propagation of the constituent quarks, coupled to the (sigma,pi) meson multiplet, on the homogeneous background of a temporal gauge field, diagonal in color space. The model is solved at finite temperature and quark baryon chemical potential both in the chiral limit and for the physical value of the pion mass by using an expansion in the number of flavors N_f. Keeping the fermion propagator at its tree-level, a resummation on the pion propagator is constructed which resums infinitely many orders in 1/N_f, where O(1/N_f) represents the order at which the fermions start to contribute in the pion propagator. The influence of the Polyakov loop on the tricritical or the critical point in the mu_q-T phase diagram is studied for various forms of the Polyakov loop potential.