In-Medium K⁺ and K^- Production and K^- Condensation in Supernova Matter

In-medium effects and neutrino trapping on K⁺ and K^- production and K^- condensation in supernova matter are investigated in a chiral hadronic model. Our results show that neutrino trapping shifts the critical density for K^- condensation to higher density, the Q values for K⁺ and K^- production are not sensitive to neutrino trapping, in-medium effects decrease the Q values for NN → NNK⁺K^- and ΛN → NNK^- and increase those for NN → NΛK⁺, K^-p → Λπ⁰ and K^-n → Λπ^- as the density of supernova matter increases. Moreover, it is shown that neutrino trapping decreases the maximum masses of protoneutron stars compared with the neutrino-free case.