Vector-Interaction-Enhanced Bag Model

TL;DR

The vBag model enhances the traditional quark matter models by explicitly including chiral symmetry breaking and vector interactions, improving the understanding of dense matter in neutron stars.

Contribution

This paper introduces the vBag model, which incorporates both chiral symmetry breaking and vector interactions into the bag model framework.

Findings

vBag accounts for chiral symmetry breaking and vector repulsion

It better explains neutron star maximum mass constraints

The model is based on Dyson-Schwinger equation analyses

Abstract

A commonly applied quark matter model in astrophysics is the thermodynamic bag model (tdBAG). The original MIT bag model approximates the effect of quark confinement, but does not explicitly account for the breaking of chiral symmetry, an important property of Quantum Chromodynamics (QCD). It further ignores vector repulsion. The vector-interaction-enhanced bag model (vBag) improves the tdBAG approach by accounting for both dynamical chiral symmetry breaking and repulsive vector interactions. The latter is of particular importance to studies of dense matter in beta-equilibriumto explain the two solar mass maximum mass constraint for neutron stars. The model is motivated by analyses of QCD based Dyson-Schwinger equations (DSE), assuming a simple quark-quark contact interaction. Here, we focus on the study of hybrid neutron star properties resulting from the application of vBag and will discuss possible extensions.