Hybrid neutron stars based on a modified PNJL model

TL;DR

This paper develops a hybrid neutron star model using a modified PNJL approach to describe quark matter, incorporating density-dependent effects and fixed couplings, and compares it with hadronic matter models to analyze mass-radius relations.

Contribution

It introduces a modified PNJL model with density-dependent Polyakov-loop potential and fixed couplings based on one-gluon exchange, applied to hybrid star EoS.

Findings

The hybrid EoS can produce neutron star masses consistent with observations.

Density dependence in the Polyakov-loop potential affects star properties.

The model links quark matter features with astrophysical constraints.

Abstract

We discuss a three-flavor Nambu--Jona-Lasinio (NJL) type quantum field theoretical approach to the quark matter equation of state (EoS) with scalar diquark condensate, isoscalar vector mean field and Kobayashi-Maskawa-'t Hooft (KMT) determinant interaction. While often the diquark and vector meson couplings are considered as free parameters, we will fix them here to their values according to the Fierz transformation of a one-gluon exchange interaction. In order to estimate the effect of a possible change in the vacuum pressure of the gluon sector at finite baryon density we exploit a recent modification of the Polyakov-loop NJL (mPNJL) model which introduces a parametric density dependence of the Polyakov-loop potential also at T=0, thus being relevant for compact star physics. We use a Dirac-Brueckner-Hartree-Fock (DBHF) EoS for the hadronic matter phase and discuss results for mass-radius relationships following from a solution of the TOV equations for such a hybrid EoS in the context of observational constraints from selected objects.