Charmonium suppression with cc̄ dissociation by strings

We study the production of cc̄ pairs in nuclear reactions at SPS energies within the covariant transport approach HSD. The production of cc̄ pairs is treated perturbatively employing experimental cross sections while the interactions of cc̄ pairs with baryons are included by conventional cascade-type two-body collisions. Adopting 6 mb for the cc̄-baryon cross section the data on J/Ψ suppression in p+A reactions are reproduced in line with calculations based on the Glauber model. Additionally the dissociation of the cc̄ pairs by strings is included in a purely geometrical way. We find good agreement with the experimental data from the NA38 and NA50 Collaborations with an estimate for the string radius of Rs≈0.2–0.25 fm.