Neutron Stars with Bose-Einstein Condensation of Antikaons as MIT Bags

TL;DR

This paper models neutron star matter with Bose-Einstein condensed antikaons using an MIT bag approach, exploring how kaon interactions influence star properties and the equation of state.

Contribution

It introduces a modified quark-meson coupling model with a density-dependent bag constant to study antikaons as MIT bags in neutron star matter, including effects of s-quark interactions.

Findings

Kaon condensation is sensitive to s-quark interactions.

Effective kaon mass varies with potential and treatment method.

Neutron star mass and radius are computed from the model.

Abstract

We investigate the properties of an antikaon in medium, regarding itas a MIT bag. We first construct the MIT bag model for a kaon with$\sigma^*$ and $\phi$ in order to describe the interaction of$s$-quarks in hyperonic matter in the framework of the modifiedquark-meson coupling model. The coupling constant $g'^{B_K}_\sigma$in the density-dependent bag constant $B(\sigma)$ is treated as afree parameter to reproduce the optical potential of a kaon in asymmetric matter and all other couplings are determined by usingSU(6) symmetry and the quark counting rule. With various values ofthe kaon potential, we calculate the effective mass of a kaon inmedium to compare it with that of a point-like kaon. We thencalculate the population of octet baryons, leptons and $K^-$ and theequation of state for neutron star matter. The results show thatkaon condensation in hyperonic matter is sensitive to the $s$-quarkinteraction and also to the way of treating the kaon. The mass andthe radius of a neutron star are obtained by solving theTolmann-Oppenheimer-Volkoff equation.