Hyperon Enhancement in the Dual Parton Model

We review the two sources of hyperon enhancement in the dual parton model: strings originating from diquark-antidiquark pairs in the nucleon sea and net baryons containing two or three sea quarks with a yield controlled by the observed stopping. We show that adding final state interactions (including strangeness exchange reactions as well as the inverse reactions required by detailed balance) with a single averaged cross-section $\sigma=0.2$ mb, we can explain the observed hyperon enhancement in PbPb collisions at CERN SPS.Comment: 6 pages, 2 eps-figure

Centrality Dependence of Hadron Multiplicities in Nuclear Collisions in the Dual Parton Model

We show that, even in purely soft processes, the hadronic multiplicity in nucleus-nucleus interactions contains a term that scales with the number of binary collisions. In the absence of shadowing corrections, this term dominates at mid rapidities and high energies. Shadowing corrections are calculated as a function of impact parameter and the centrality dependence of mid-rapidity multiplicities is determined. The multiplicity per participant increases with centrality with a rate that increases between SPS and RHIC energies, in agreement with experiment.Comment: 15 pages, 4 postscript figure

Charged Multiplicities at SPS and RHIC and consequences for J/ψJ/\psi suppression

Hadron multiplicities in nucleus--nucleus interactions are calculated in the Dual Parton Model and its dependence on the number of collisions and the number of participants is analyzed. Shadowing corrections are calculated as a function of impact parameter and the multiplicity per participant as a funtion of centrality is found to be in agreement with experiment at SPS and RHIC energies. The obtained results are used to compute the $J/\psi$ suppression in a comover approach.Comment: 4 pages, 4 postscript figures. Talk given at XXXVI Rencontres de Moriond, Les Arcs, France, March 200