DIPARTAMENTO DI FISICA ”G.Galilei” ISTITUTO DI FISICA NUCLEARE

In this report we have made a systematic study of strangeness production in proton-proton(pp),proton-nucleus(pA) and nucleusnucleus(AA) collisions at CERN Super Proton Synchroton energies, using HIJING MONTE CARLO MODEL (version HIJ.01). Numerical results for mean multiplicities of neutral strange particles ,as well as their ratios to negatives hadrons(< h >) for p-p,nucleon-nucleon(N-N), p-S, pAg, p-Au(’min. bias’)collisions and p-Au, S-S, S-Ag, S-Au (’central’)collisions are compared to experimental data available from CERN experiments and also with recent theoretical estimations given by others models( QGSM, RQMD, DPM, V ENUS and FRITIOF ). Neutral strange particle abundances are quite well described for p-p,N-N and p-A interactions ,but are underpredicted by a factor of two in A-A interactions for Λ, Λ̄,K0 S in symmetric collisions(S-S, Pb-Pb)and for Λ, Λ̄ in asymmetric ones(SAg, S-Au, S-W). The ratios antistrange/strange are well described for Λ̄Λ but the ratios for multistrange particles (Ξ,Ω ) and their antiparticle, could not be predicted by the model.A detailed analysis in limited rapidity range is required in order to draw some definite conclusion. A qualitative prediction for rapidity, transverse kinetic energy and transverse momenta normalized distributions are performed at 200 GeV/Nucleon in p-S,S-S,SAg and S-Au collisions in comparison with recent experimental data. HIJING model predictions for coming experiments at CERN for S-Au, S-W and Pb-Pb interactions are given. The theoretical calculations are estimated in a full phase space. The factor of two can not be explained by considering very central events (bmax = 0.0) and taking into account minijets. New ideas are necessary in order to improve the comparison with experiment for nucleus nucleus interactions. ∗On leave from absence from Institute for Space Sciences,P.O.Box MG 6,Bucharest, Romania EMAIL [email protected](EARN);[email protected]