Hybrid neutron stars within the Nambu-Jona-Lasinio model and confinement

TL;DR

This paper investigates the limitations of the Nambu-Jona-Lasinio model in describing quark matter in neutron stars, highlighting issues with stability and the absence of confinement, despite modified cutoff procedures.

Contribution

It demonstrates that even with a density-dependent cutoff, the pure quark phase remains unstable in neutron stars, emphasizing the need to incorporate confinement effects.

Findings

Pure quark phase in neutron stars is unstable.

Modified cutoff procedures do not stabilize the quark phase.

Lack of confinement in NJL model affects neutron star modeling.

Abstract

Recently, it has been shown that the standard Nambu-Jona-Lasinio (NJL) model is not able to reproduce the correct QCD behavior of the gap equation at large density, and therefore a different cutoff procedure at large momenta has ben proposed. We found that, even with this density dependent cutoff procedure, the pure quark phase in neutron stars (NS) interiors is unstable, and we argue that this could be related to the lack of confinement in the original NJL model.