Properties of a kaon-condensed phase in hyperon-mixed matter with three-baryon forces

TL;DR

This paper investigates the properties of a dense hadronic phase with kaon condensates and hyperons, incorporating three-baryon forces, and examines its implications for neutron star equations of state and observable properties.

Contribution

It introduces a comprehensive model combining chiral dynamics, baryon interactions, and three-baryon forces to analyze the ($Y$+$K$) phase in dense matter, highlighting the effects on neutron star properties.

Findings

The ($Y$+$K$) phase can produce a stiff equation of state compatible with massive neutron stars.

The slope of the symmetry energy influences the onset of kaon condensation and hyperon admixture.

Three-baryon repulsion significantly affects the high-density behavior of dense matter.

Abstract

Coexistent phase of kaon condensates and hyperons [($Y$+$K$) phase] in beta equilibrium with electrons and muons is investigated as a possible form of dense hadronic phase with multi-strangeness. The effective chiral Lagrangian for kaon-baryon and kaon-kaon interactions is utilized within chiral symmetry approach in combination with the interaction model between baryons. For the baryon-baryon interactions, we adopt the minimal relativistic mean-field theory with exchange of scalar mesons and vector mesons between baryons without including the nonlinear self-interacting meson field terms. In addition, the universal three-baryon repulsion and the phenomenological three-nucleon attraction are introduced as density-dependent effective two-body potentials. The repulsive effects leading to stiff equation of state at high densities consist of both the two-baryon repulsion via the vector-meson exchange and the universal three-baryon repulsion. Interplay of kaon condensates with hyperons through chiral dynamics in dense matter is clarified, and resulting onset mechanisms of kaon condensation in hyperon-mixed matter and the equation of state with the ($Y$+$K$) phase and characteristic features of the system are presented. It is shown that the slope $L$ of the symmetry energy controls the two-baryon repulsion beyond the saturation density and resulting stiffness of the equation of state. The stiffness of the equation of state in turn controls admixture of hyperons and the onset and development of kaon condensates as a result of competing effect between kaon condensates and hyperons. The equation of state with the ($Y$+$K$) phase becomes stiff enough to be consistent with recent observations of massive neutron stars. Static properties of neutron stars with the ($Y$+$K$) phase are discussed.