The phase structure of a chiral model with dilatons in hot and dense matter

TL;DR

This paper investigates the phase transitions in a chiral model with dilatons at finite temperature and density, revealing complex interplay between chiral and scale symmetries and identifying conditions for their restoration or breaking.

Contribution

It introduces a chiral model incorporating dilaton fields to study the coupled dynamics of chiral and scale symmetries at finite temperature and chemical potential.

Findings

Chiral phase transition occurs with increasing temperature.

A first-order phase transition of partial scale symmetry restoration is observed.

A region exists where scale symmetry remains broken while chiral symmetry is restored.

Abstract

We explore the phase structure of a chiral model of constituent quarks and gluons implementing scale symmetry breaking at finite temperature and chemical potential. In this model the chiral dynamics is intimately linked to the trace anomaly saturated by a dilaton field. The thermodynamics is governed by two condensates, thermal expectation values of sigma and dilaton fields, which are the order parameters responsible for the phase transitions associated with the chiral and scale symmetries. Within the mean field approximation, we find that increasing temperature a system experiences a chiral phase transition and then a first-order phase transition of partial scale symmetry restoration characterized by a melting gluon-condensate takes place at a higher temperature. There exists a region at finite chemical potential where the scale symmetry remains dynamically broken while the chiral symmetry is restored. We also give a brief discussion on the sigma-meson mass constrained from Lattice QCD.