Energy dependence of Λ and Χ production in central Pb+Pb collisions at A-20, A-30, A-40, A- 80, and A-158 GeV measured at the CERN Super Proton Synchrotron

Results on Λ, Λ, X-, X+ production in central Pb+Pb reactions at 20A, 30A, 40A, 80A, and 158A GeV are presented. The energy dependence of transverse mass spectra, rapidity spectra, and multiplicities is discussed. Comparisons to string hadronic models (UrQMD and HSD) and statistical hadron gas models are shown. While the latter provide a reasonable description of all particle yields, the first class of models fails to match the X- and X+ multiplicities.