Kaons and antikaons in nuclear matter: AA vs. pA collisions

Kaon- and antikaon production near the threshold is studied within a transport approach of Boltzmann-Uehling-Uhlenbeck type with the aim of a concise understanding of medium modifications. The role of (i) the strangeness-exchange reaction πY → K- N, (ii) the feeding of φ→ K+K- and (iii) different models of K±N potentials with momentum dependence is elaborated. We compare our transport model calculations to experimental phase space distributions of K± in the reactions p+C, p+Au, C+C and Ar+KCl (KaoS and HADES data).