Baryon and antibaryon production in hadronic and nuclear interactions

We introduce a new formulation of the diquark breaking mechanism which desc ribes with no free parameters the huge nuclear stopping observed in central nucleus-nucleus collisions. Supplemented, in the dual parton model, with s trings 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 undere stimated for Lambda's and Xi's but is five times too small for Omega's. Int roducing final state interactions, a reasonable description of all baryon a nd antibaryon yields is achieved. (C) 1999 Elsevier Science B.V. All rights reserved.