Kaonic modes in hyperonic matter and p-wave kaon condensation Original Research Article

Kaon excitations (kaonic modes) are investigated in hyperonic matter, where hyperons (Λ, Σ−, Ξ− ) are mixed in the ground state of neutron-star matter. P-wave kaon–baryon interactions as well as the s-wave interactions are taken into account within chiral effective Lagrangian, and the nonrelativistic effective baryon–baryon interactions are incorporated. When the hyperon Λ is more abundant than the proton at high baryon density, a proton-particle–Λ-hole mode, which has the K+ quantum number, appears in addition to other particle–hole modes with the K− quantum number. It is shown that the system becomes unstable with respect to a spontaneous creation of a pair of the particle–hole modes with K+ and K− quantum numbers, stemming from the p-wave kaon–baryon interaction. The onset density of this p-wave kaon condensation may be lower than that of the s-wave K− condensation.