Review of SIS experimental results on strangeness

Abstract

A review of meson emission in heavy-ion collisions at incident energiesaround 1-2 A GeV is presented. It is shown how the shape of thespectra and the various particle yields vary with system size, withcentrality and with incident energy. A statistical model assuming thermaland chemical equilibrium and exact strangeness conservation (i.e. strangeness conservation per collision)explains most of the observed features.Emphasis is put on the study of K+ and K- emission. Within theframework of this statistical model it is shown that the experimentallyobserved equality of K+ and K- rates at threshold correctedenergies is due to a crossing of two excitationfunctions. Furthermore, the independence of the K+ to K-ratio of the number of participating nucleons observedbetween 1 and 10 A GeV is consistent with this model.The observed flow effects are beyond the scope of thismodel.