Isentropic thermodynamics in the PNJL model

TL;DR

This paper investigates isentropic trajectories in the QCD phase diagram using the PNJL model, comparing numerical results with lattice QCD estimates and analyzing the role of strange quark chemical potential.

Contribution

It introduces a method to impose zero strange quark density in the PNJL model and compares it with lattice QCD Taylor expansion estimates.

Findings

Numerical results align with truncated Taylor expansion estimates.

Strangeness neutrality influences the strange quark chemical potential.

The ratio of Polyakov loop to anti-Polyakov loop relates to strangeness neutrality.

Abstract

We discuss the isentropic trajectories on the QCD phase diagram in the temperature and the quark chemical potential plane using the Nambu--Jona-Lasinio model with the Polyakov loop coupling (PNJL model). We impose a constraint on the strange quark chemical potential so that the strange quark density is zero, which is the case in the ultra relativistic heavy-ion collisions. We compare our numerical results with the truncated estimates by the Taylor expansion in terms of the chemical potential to quantify the reliability of the expansion used in the lattice QCD simulation. We finally discuss the strange quark chemical potential induced by the strangeness neutrality condition and relate it to the ratio of the Polyakov loop and the anti-Polyakov loop.