Nonlocal Polyakov-Nambu-Jona-Lasinio model and imaginary chemical potential

TL;DR

This paper investigates the phase structure of a nonlocal PNJL model with vector interactions at imaginary chemical potentials, successfully reproducing key QCD features and analyzing the RW transition and endpoint.

Contribution

It introduces an advanced nonlocal PNJL model with wave-function-renormalization and vector interactions, aligning with lattice QCD results at imaginary chemical potentials.

Findings

Reproduces Roberge-Weiss periodicity and transition.

Chiral and deconfinement transitions coincide at various chemical potentials.

Analyzes the nature of the RW endpoint and its first-order transition.

Abstract

With the aim of setting constraints for the modeling of the QCD phase diagram, the phase structure of the two-flavor Polyakov-loop extended Nambu and Jona-Lasinio (PNJL) model is investigated in the range of imaginary chemical potentials ($\mu_\mathrm{I}$) and compared with available $N_f=2$ lattice QCD results. The calculations are performed using the advanced nonlocal version of the PNJL model with the inclusion of vector-type quasiparticle interactions between quarks, and with wave-function-renormalization corrections. It is demonstrated that the nonlocal PNJL model reproduces important features of QCD at finite $\mu_\mathrm{I}$, such as the Roberge-Weiss (RW) periodicity and the RW transition. Chiral and deconfinement transition temperatures for $N_f=2$ turn out to coincide both at zero chemical potential and at finite $\mu_\mathrm{I}$. Detailed studies are performed concerning the RW endpoint and its neighborhood where a first-order transition occurs.