Direct comparison of phase-space distributions of K- and K+ mesons in heavy-ion collisions at SIS energies -- evidence for in-medium modifications of kaons?
Abstract:The ratio of K- to K+-meson yields has been measured in the systems 96Ru + 96Ru at 1.69 A GeV, 96Ru+96Zr at 1.69 A GeV, and 58Ni+58Ni at 1.93 A GeV incident beam kinetic energy. The yield ratio is observed to vary across the measured phase space. Relativistic transport-model calculations indicate that the data are best understood if in-medium modifications of the kaons are taken into account.