QCD Equation of State From a Chiral Hadronic Model Including Quark Degrees of Freedom

TL;DR

This paper introduces an effective model for QCD matter that combines hadron and quark degrees of freedom, capturing chiral symmetry restoration and deconfinement transitions, and aligns well with lattice QCD results.

Contribution

The model integrates hadron and quark phases with a unified approach to describe the QCD phase diagram across a wide range of temperatures and densities.

Findings

The phase diagram matches lattice QCD results at small chemical potentials.

Heavy-mass resonance states significantly influence the chiral transition.

The model successfully describes the chiral and deconfinement phase transitions.

Abstract

This work presents an effective model for strongly interacting matter and the QCD equation of state (EoS). The model includes both hadron and quark degrees of freedom and takes into account the transition of chiral symmetry restoration as well as the deconfinement phase transition. At low temperatures $T$ and baryonic densities $\rho_B$ a hadron resonance gas is described using a SU(3)-flavor sigma-omega model and a quark phase is introduced in analogy to PNJL models for higher $T$ and $\rho_B$. In this way, the correct asymptotic degrees of freedom are used in a wide range of $T$ and $\rho_B$. Here, results of this model concerning the chiral and deconfinement phase transitions and thermodynamic model properties are presented. Large hadron resonance multiplicities in the transition region emphasize the importance of heavy-mass resonance states in this region and their impact on the chiral transition behavior. The resulting phase diagram of QCD matter at small chemical potentials is in line with latest lattice QCD and thermal model results.