Formation of droplets with high baryon density at the QCD phase transition in expanding matter

TL;DR

This paper models the (3+1)D expansion of quark-gluon matter at finite baryon density, showing how inhomogeneities and droplet formation occur during the QCD phase transition, especially in the spinodal region.

Contribution

It introduces a dynamical model coupling chiral fields and the Polyakov loop to a quark-antiquark fluid, capturing fluctuations and inhomogeneities during the QCD phase transition.

Findings

Inhomogeneities in net-baryon density can form during the spinodal region.

The model demonstrates differences in transition dynamics through crossover and critical end point.

Droplet formation is enhanced during the first-order phase transition.

Abstract

We consider the (3+1) dimensional expansion and cooling of the chirally-restored and deconfined matter at finite net-baryon densities as expected in heavy-ion collisions at moderate energies. In our approach, we consider chiral fields and the Polyakov loop as dynamical variables coupled to a medium represented by a quark-antiquark fluid. The interaction between the fields and the fluid leads to dissipation and noise, which in turn affect the field fluctuations. We demonstrate how inhomogeneities in the net-baryon density may form during an evolution through the spinodal region of the first-order phase transition. For comparison, the dynamics of transition through the crossover and critical end point is also considered.