Flavor production in Pb(160A GeV) on Pb collisions: Effect of color ropes and hadronic rescattering.

Abstract

Collective interactions in the preequilibrium quark matter and hadronic resonance gas stage of ultrarelativistic nucleus-nucleus collisions are studied in the framework of the transport theoretical approach RQMD. The paper reviews string fusion into color ropes and hadronic rescattering which serve as models for these interactions. Hadron production in central Pb(160A GeV) on Pb collisions has been calculated. The changes of the final flavor composition are more pronounced than in previous RQMD studies of light ion induced reactions at 200A GeV. The ratio of created quark pairs ss\ifmmode\bar\else\textasciimacron\fi{}/(u\ifmmode \bar{u}\else \={u}\fi{}+dd\ifmmode\bar\else\textasciimacron\fi{}) is enhanced by a factor of 2.4 in comparison to pp results. Color rope formation increases the initially produced antibaryons to 3 times the value in the ``NN mode,'' but only one quarter of the produced antibaryons survives because of subsequent strong absorption. The differences in the final particle composition for Pb on Pb collisions compared to S-induced reactions are attributed to the hadronic resonance gas stage which is baryon-richer and lasts longer.