Vector interaction, charge neutrality and multiple chiral critical point structures

TL;DR

This paper explores how vector interactions and electric chemical potential influence the chiral phase transition and critical point structures in NJL models, revealing multiple critical points and stabilization effects in neutral quark matter.

Contribution

It demonstrates the existence of up to four chiral critical points in NJL models and analyzes how vector interactions affect phase stability and critical structures.

Findings

Multiple chiral critical points can exist depending on interaction strengths.

Vector interactions suppress chromomagnetic instability in neutral CSC.

Number of critical points varies from zero to four.

Abstract

We investigate the combined effect of the repulsive vector interaction and the positive electric chemical potential on the chiral phase transition by considering neutral color superconductivity (CSC). The chiral condensate, diquark condensate and quark number densities are solved in both two-flavor and two-plus-one-flavor Nambu-Jona-Lasinio(NJL) models with the so called Kobayashi-Maskawa-'t Hooft term under the charge neutrality constraint. We demonstrate that multiple chiral critical-point structures always exist in the NJL model within the self-consistent mean-field approximation and the number of chiral critical points can vary from zero to four, which is dependent on the magnitudes of vector interaction and the diquark coupling. The difference between the dynamical chemical potentials induced by vector interaction for u and d quarks can effectively reduce the Fermi sphere disparity between the two flavors of diquark paring. Thus the vector interaction works to significantly suppress the unstable region associated with chromomagnetic instability in the phase of neutral asymmetric homogenous CSC.