System-size dependence of $\Lambda$ and $\Xi$ production in nucleus-nucleus collisions at 40A and 158A GeV measured at the CERN Super Proton Synchrotron

Results on Lambda, Anti-lambda, and Xi- production in centrality selected Pb+Pb reactions at 40A and 158A GeV and in near-central C+C and Si+Si reactions at 158A GeV are presented. Transverse mass spectra, rapidity spectra, and multiplicities in dependence of the system size are discussed. Comparisons to transport models (UrQMD2.3 and HSD) and to the core-corona approach are performed. While Lambda and Anti-lambda production can be described by transport models reasonably well, these models do not agree with the Xi- measurements. On the other hand, the core-corona picture fits very well the system-size dependence of Lambda and Xi-, while it agrees less well with the Anti-lambda data.
13 pages, 12 figures. Revised version as accepted by Phys. Rev. C