Higher-order baryon number susceptibilities: interplay between the chiral and the nuclear liquid-gas transitions

TL;DR

This paper employs an improved SU(3) parity-doublet quark-hadron model to study higher-order baryon number susceptibilities, revealing a significant interplay between chiral and nuclear liquid-gas transitions affecting experimental cumulant measurements.

Contribution

It introduces higher-order scalar interactions into the parity-doublet model, enhancing the description of nuclear properties and phase diagram features relevant to QCD transitions.

Findings

Phase diagram shows crossover at zero chemical potential and a critical point at finite density.

Strong interplay observed between chiral and liquid-gas transitions at intermediate densities.

Baryon number cumulants vary significantly with freeze-out temperature and transition interplay.

Abstract

We use an improved version of the SU(3) flavour parity-doublet quark-hadron model to investigate the higher order baryon number susceptibilities near the chiral and the nuclear liquid-gas transitions. The parity-doublet model has been improved by adding higher-order interaction terms of the scalar fields in the effective mean field Lagrangian, resulting in a much-improved description of nuclear ground-state properties, in particular the nuclear compressibility. The resulting phase diagram of the model agrees qualitatively with expectations from lattice QCD, i.e., it shows a crossover at zero net baryo-chemical potential and a critical point at finite density. Using this model, we investigate the dependence of the higher-order baryon number susceptibilities as function of temperature and chemical potential. We observe a strong interplay between the chiral and liquid-gas transition at intermediate baryo chemical potentials. Due to this interplay between the chiral and the nuclear liquid-gas transitions, the experimentally measured cumulants of the net baryon number may show very different beam energy dependence, subject to the actual freeze-out temperature.