Baryon and Antibaryon Production in Hadronic and Nuclear Interactions

We introduce a new formulation of the diquark breaking mechanism which describes with no free parameters the huge nuclear stopping observed in central nucleus-nucleus collisions. Supplemented, in the dual parton model, with strings originating from diquark--antidiquark pairs from the nucleon sea, it gives a substantial increase of hyperon and antihyperon yields from $pPb$ to central $PbPb$ collisions. Compared to data, this increase is slightly underestimated for $\Lambda$'s and $\Xi$'s but is five times too small for $\Omega$'s. Introducing final state interactions, a reasonable description of all baryon and antibaryon yields is achieved.