QCD Thermodynamics: Lattice Results confront Models

TL;DR

This paper compares lattice QCD results at finite temperature and density with the hadron resonance gas model, revealing agreement up to near the critical temperature and a transition towards free field behavior at higher temperatures.

Contribution

It provides a detailed comparison between lattice QCD data and effective models, highlighting the relationship between chiral symmetry and confinement across temperature regimes.

Findings

Lattice results agree with the hadron resonance gas model up to 0.95 Tc.

At T ≥ 1.5 Tc, QCD approaches free field behavior with fewer effective flavors.

The critical line of QCD shows similarities with simple models sharing the same symmetries.

Abstract

We show that lattice results on four flavor QCD at nonzero temperature and baryon density compare well with the hadron resonance gas model up to T approx. 0.95 Tc, and approach a free field behaviour with a reduced effective number of flavor for T \ge 1.5 Tc. Chiral symmetry and confinement are interrelated, and we note analogies between the critical line of QCD and that of simple models with the same global symmetries.