KAON POLARIZATION IN NUCLEAR-MATTER

The kaon-nucleon interaction in nuclear matter is considered by taking into account tree graphs, p-wave interaction, pionic intermediate states, kaon fluctuations and some residual interaction. The latter one is constrained by Adler's consistency condition. The K-, K+, K-0, (K) over bar(0) polarization operators are calculated in cold nuclear matter with arbitrary isotopic composition. An extra s-wave repulsion is found, which probably shifts the critical point of a K- condensation with vanishing kaon momentum to large nucleon densities. Oppositely, an extra p-wave attraction is obtained, which may lead to a K- condensation at vanishing temperatures and densities rho greater than or equal to rho(c)(-) similar to(4-6)rho(0). The spectrum of the kaonic excitations in nuclear matter is analyzed and a new low-lying branch in the K- (and also (K) over bar(0)) spectrum is found. Its presence may lead to interesting observable consequences, such as the enhancement of the K- yields in heavy-ion reactions. At rho greater than or equal to rho(c)(-) the frequency of this low-lying branch becomes negative at non-vanishing momentum; that signals the onset of a new type inhomogeneous K- condensation. The K- condensate energy is calculated in the approximation of a small KK coupling constant. Accordingly, neutron star matter may undergo a first-order phase transition to proton matter with K- condensate at rho > rho(c)(-) due to p-wave interaction. The temperature dependence of the most important terms of the K- polarization operator is discussed. In a rather wide temperature region 0 < T < 1/2m(pi) a growing temperature enlarges the K-N attraction and promotes the kaon condensation. The possibility of p-wave (K) over bar(0) condensation is also considered. The question is qualitatively discussed whether proton matter with K- condensate or neutron matter with (K) over bar(0) condensate is energetically more favorable.