Critical surface in hot and dense QCD with the vector interaction

TL;DR

This paper investigates how the vector interaction influences the chiral phase transition in hot and dense QCD, revealing that strong vector coupling can diminish the first-order transition region, aligning with recent lattice QCD findings.

Contribution

It demonstrates how the vector interaction modifies the QCD critical surface and the nature of the phase transition using the NJL model with Polyakov loop coupling.

Findings

First-order transition region shrinks with increasing vector coupling.

Large vector coupling can explain recent lattice QCD results.

The critical surface depends on the quark mass and chemical potential.

Abstract

We discuss the chiral phase transition of hot and dense quark matter. We illustrate that the first-order phase transition is generally favored at high baryon density and the repulsive vector-vector interaction weakens the first-order phase transition. We use the Nambu--Jona-Lasinio model with the Polyakov loop coupling for concreteness. We locate the QCD critical surface on the quark mass plane for various values of the vector coupling constant. We find that, with increasing quark chemical potential, the first-order region in the quark mass plane could shrink for sufficiently large vector coupling. This may be a possible explanation for the recent lattice QCD results by de Forcrand and Philipsen.