Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

First Measurement of Antikaon Phase-Space Distributions in Nucleus-Nucleus Collisions at Subthreshold Beam Energies

Menzel, M.; Böttcher, I.; Debowski, M.; Dohrmann, F.; Förster, A.; Grosse, E.; Koczon, P.; Kohlmeyer, B.; Laue, F.; Naumann, L.; Oeschler, H.; Pülhofer, F.; Schwab, E.; Senger, P.; Shin, Y.; Ströbele, H.; Sturm, C.; Surowka, G.; Uhlig, F.; Wagner, A.; Walus, W.

Differential production cross sections of K- and K+ mesons have been measured as function of the polar emission angle in Ni+Ni collisions at a beam energy of 1.93 AGeV. In near-central collisions, the spectral shapes and the widths of the rapidity distributions of K- and K+ mesons are in agreement with the assumption of isotropic emission. In non-central collisions, the K- and K+ rapidity distributions are broader than expected for a single thermal source. In this case, the polar angle distributions are strongly forward-backward peaked and the nonisotropic contribution to the total yield is about one third both for K+ and K- mesons. The K-K+ ratio is found to be about 0.03 independent of the centrality of the reaction. This value is significantly larger than predicted by microscopic transport calculations if in-medium modifications of K mesons are neglected.

  • Physics Letters B, 495 (2000) 26-32

Publ.-Id: 5425