PRODUCTION AND ABSORPTION OF C(C)OVER-BAR PAIRS IN NUCLEAR COLLISIONS AT SPS ENERGIES

摘要

We study the production of c (c) over bar pairs and dimuons from hard collisions in nuclear reactions within the covariant transport approach HSD, which describes successfully both hadronic and electromagnetic observables from p + A and A + A collisions from SIS to SPS energies. The production of c (c) over bar and Drell-Yan pairs is treated perturbatively employing experimental cross sections while the interactions of c (c) over bar pairs with hadrons are included by conventional cascade-type two-body collisions. Adopting 6 mb for the c (c) over bar-baryon cross sections the data on J/Psi suppression in p + A reactions are reproduced in line with calculations based on the Glauber model. We study different models for c (c) over bar dissociation on mesons in comparison with the experimental data of the HELIOS-3, NA38 and NA50 collaborations. Adopting absorption cross sections with mesons above the D (D) over bar threshold in the order of 1.5-3 mb we find that all data on J/Psi suppression from both proton-nucleus and nucleus-nucleus collisions can be described without assuming the formation of a quark-gluon plasma in these collisions. (C) 1997 Elsevier Science B.V. [References: 42]