Thermodynamic instabilities in dynamical quark models with complex conjugate mass poles

TL;DR

This paper demonstrates that dynamical quark models with complex conjugate mass poles inherently exhibit thermodynamic instabilities, which can be mitigated but not fully eliminated by coupling to a Polyakov loop potential.

Contribution

It reveals the inevitability of thermodynamic instabilities in such quark models and explores the partial suppression effect of Polyakov loop coupling.

Findings

Thermodynamic potential shows instabilities in models with complex conjugate mass poles.

Coupling to Polyakov loop potential reduces but does not eliminate these instabilities.

The effect is explicitly demonstrated in a covariant, chirally symmetric quark model.

Abstract

We show that the CJT thermodynamic potential of dynamical quark models with a quark propagator represented by complex conjugate mass poles inevitably exhibits thermodynamic instabilities. We find that the minimal coupling of the quark sector to a Polyakov loop potential can strongly suppress but not completely remove such instabilities. This general effect is explicitly demonstrated in the framework of a covariant, chirally symmetric, effective quark model.