Influence of the isovector-scalar channel interaction on neutron star matter with hyperons and antikaon condensation

Abstract

The relativistic mean field approach including isovector-scalar channel (i.e., exchanging $\ensuremath{\delta}$ mesons) interaction is taken to study the properties of neutron star matter including hyperons and antikaon condensation. For hyperonic neutron stars, it shows that the $\ensuremath{\delta}$-meson channel interaction stiffens the equation of state at lower densities but it softens the equation of state after hyperons appear. This leads to the neutron star having a lower central density and a larger radius than the one with the same mass but without the $\ensuremath{\delta}$-meson channel interaction. For neutron star matter including both hyperons and antikaon condensation, the $\ensuremath{\delta}$-meson channel interaction increases the onset density of the antikaon condensation. At the same time, the stability of the kaonic neutron star and its dependence on the kaon optical potential are discussed. For stable kaonic neutron stars with larger radii, those with the inclusion of the $\ensuremath{\delta}$-meson channel interaction have larger masses than those without the $\ensuremath{\delta}$-meson interaction, but the result is reversed for those with smaller radii. Calculated results are also compared with neutron star observations. Constraints on the model parameters are then provided.