Fluctuations and correlations in Polyakov loop extended chiral fluid dynamics

TL;DR

This paper investigates nonequilibrium effects during the QCD phase transition using a Polyakov loop extended chiral fluid dynamics model, revealing long-range correlations and fluctuation enhancements at different transition types.

Contribution

It introduces a dynamical framework combining Langevin equations for quark, sigma, and Polyakov loop fields to study fluctuations during the QCD phase transition.

Findings

Long-range correlations form at the critical point.

Fluctuations are enhanced during first-order phase transitions.

Nonequilibrium effects significantly influence the transition dynamics.

Abstract

We study nonequilibrium effects at the QCD phase transition within the framework of Polyakov loop extended chiral fluid dynamics. The quark degrees of freedom act as a locally equilibrated heat bath for the sigma field and a dynamical Polyakov loop. Their evolution is described by a Langevin equation with dissipation and noise. At a critical point we observe the formation of long-range correlations after equilibration. During a hydrodynamical expansion nonequilibrium fluctuations are enhanced at the first order phase transition compared to the critical point.