K⁰ Condensation in Hyperonic Neutron Star Matter

In the framework of the relativistic mean field theory, we investigate K⁰ condensation along with K^- condensation in neutron star matter including the baryon octet. The results show that both K⁰ and K^- condensations can occur well in the core of the maximum mass stars for relatively shallow optical potentials of K in the range of -100MeV~ -160MeV. With the increasing optical potential of K, the critical densities of K decrease and the species of baryons appearing in neutron stars become fewer. The main role of K⁰ condensation is to make the abundances of particles become identical leading to isospin saturated symmetric matter including antikaons, nucleons and hyperons. K^-
condensation is chiefly responsible for the softening of the corresponding equation of state, which leads to a large reduction in the maximum masses of neutron stars. In the core of massive neutron stars, neutron star matter including rich particle species, such as antikaons, nucleons and hyperons, may exist.