Compact stars with a quark core within NJL model

TL;DR

This paper uses a modified NJL model with a chemical potential-dependent cutoff to study hybrid stars, demonstrating the possibility of stable quark-core stars and effects on the equation of state.

Contribution

It introduces a new cutoff parametrization in the NJL model that enables the modeling of stable hybrid stars with quark cores.

Findings

Stable hybrid stars with quark cores are possible.

Larger cutoff leads to earlier s quark appearance in stellar matter.

Equation of state softens with increased cutoff.

Abstract

An ultraviolet cutoff dependent on the chemical potential as proposed by Casalbuoni {\it et al} is used in the su(3) Nambu-Jona-Lasinio model. The model is applied to the description of stellar quark matter and compact stars. It is shown that with a new cutoff parametrization it is possible to obtain stable hybrid stars with a quark core. A larger cutoff at finite densities leads to a partial chiral symmetry restoration of quark $s$ at lower densities. A direct consequence is the onset of the $s$ quark in stellar matter at lower densities and a softening of the equation of state.