Conserved Charge Fluctuations in a Chiral Hadronic Model including Hadrons and Quarks

TL;DR

This paper investigates quark number susceptibilities in a chiral hadronic model with quarks and gluons, revealing how fluctuations signal the transition from hadrons to quarks and how vector interactions influence these fluctuations.

Contribution

It introduces a comprehensive model combining hadronic and quark degrees of freedom to analyze charge fluctuations across the deconfinement transition.

Findings

Susceptibilities sharply increase at the critical temperature.

Vector interactions suppress fluctuations in the hadronic phase.

Quark fluctuations are quenched by vector interactions above T_c.

Abstract

In this work the susceptibility coefficients of the strange and non-strange quark number of second and fourth order are presented. The results at zero baryonchemical potential are obtained using a well tested chiral effective model including all known hadron degrees of freedom and additionally incorporating quarks and gluons in a PNJL model approach. Quark number susceptibilities are sensitive to the fundamental degrees of freedom in the model and signal the shift from massive hadrons to light quarks at the deconfinement transition by a sharp rise at the critical temperature. Furthermore, all susceptibilities are found to be largely suppressed by repulsive vector field interactions of the particles. In the hadronic sector vector repulsion of baryon resonances restrains fluctuations to a region determined in lattice QCD. However, in the quark sector above $T_c$ even small vector field interactions of quarks quench all fluctuations almost completely. For this reason, vector field interactions for quarks have to vanish in the deconfinement limit.