Kaon Condensation in Hyperonic Matter and Structure of Neutron Stars

The effects of kaon condensates on the equation of state (EOS) in hyperonic matter, where hyperons (Λ, Σ-) are mixed in the ground state of neutron-star matter, are investigated. In the fully-developed phase of kaon condensation, it is shown that the EOS is much softened due to the s-wave kaon-baryon interactions as well as due to the hyperon-mixing. As a result, the energy of the system has a local minimum, which leads to a metastable self-bound kaon-condensed star in addition to a kaon-condensed star obtained by Maxwell's construction. The lifetime of the metastable state of the kaon-condensed bound star is estimated.