QCD equation of state in a virial expansion

TL;DR

This paper models the QCD equation of state across phases using a virial expansion, incorporating non-perturbative effects and finite density extensions, and compares results with lattice data to explore phase diagram features.

Contribution

It introduces a virial expansion framework for three-flavor QCD that includes non-perturbative effects and finite chemical potential dependence, extending previous models.

Findings

Reproduces lattice QCD results for pressure and other thermodynamic quantities.

Provides a detailed phase diagram with critical endpoint analysis.

Extends the virial approach to finite quark densities.

Abstract

We describe recent three-flavor QCD lattice data for the pressure, speed of soun d and interaction measure at nonzero temperature and vanishing chemical potentia l within a virial expansion. For the deconfined phase we use a phenomenological model which includes non-pert urbative effects from dimension two gluon condensates that reproduce the free en ergy of quenched QCD very well. The hadronic phase is parameterized by a generalized resonance-gas model. Furthermore, we extend this approach to finite quark densities introducing an ex plicit $\mu$-dependence of the interaction. We calculate pressure, quark-number density, entropy and energy density and compare to results of lattice calculatio ns. We, additionally, investigate the structure of the phase diagram by calculating the isobaric and isentropic lines as well as the critical endpoint in the ($T, \mu_q $)-plane.