Fluctuations and Correlations of Conserved Charges in QCD at Finite Temperature with Effective Models

TL;DR

This paper investigates fluctuations and correlations of conserved charges in QCD at finite temperature using an effective Polyakov--Nambu--Jona-Lasinio model, comparing results with lattice QCD and identifying signatures of phase transitions.

Contribution

It demonstrates that the PNJL model can reproduce lattice QCD results for conserved charge fluctuations and highlights the cusp in baryon number fluctuation ratios as a phase transition indicator.

Findings

PNJL model results align well with lattice QCD data.

A pronounced cusp in baryon number fluctuation ratio at the critical temperature.

Fluctuation ratios serve as probes for deconfinement and chiral phase transitions.

Abstract

We study fluctuations of conserved charges including baryon number, electric charge, and strangeness as well as the correlations among these conserved charges in the 2+1 flavor Polyakov--Nambu--Jona-Lasinio model at finite temperature. The calculated results are compared with those obtained from recent lattice calculations performed with an improved staggered fermion action at two values of the lattice cutoff with almost physical up and down quark masses and a physical value for the strange quark mass. We find that our calculated results are well consistent with those obtained in lattice calculations except for some quantitative differences for fluctuations related with strange quarks. Our calculations indicate that there is a pronounced cusp in the ratio of the quartic to quadratic fluctuations of baryon number, i.e. $\chi_{4}^{B}/\chi_{2}^{B}$, at the critical temperature during the phase transition, which confirms that $\chi_{4}^{B}/\chi_{2}^{B}$ is a useful probe of the deconfinement and chiral phase transition.