Open charm and charmonium production at relativistic energies -: art. no. 054905

We calculate open charm and charmonium production in Au+Au reactions at roots=200 GeV within the hadron-string dynamics transport approach, employing open charm cross sections from pN and piN reactions that are fitted to results from PYTHIA and scaled in magnitude to the available experimental data. Charmonium dissociation with nucleons and formed mesons to open charm (D+(D) over bar pairs) is included dynamically. The "comover" dissociation cross sections are described by a simple phase-space model including a single free parameter, i.e., an interaction strength M-0(2) that is fitted to the J/Psi suppression data for Pb+Pb collisions at Super Proton Synchrotron (SPS) energies. As a novel feature we implement the backward channels for charmonium reproduction by D (D) over bar channels employing detailed balance. From our dynamical calculations we find that the charmonium re-creation is comparable to the dissociation by "comoving" mesons. This leads to the final result that the total J/Psi suppression at roots=200 GeV as a function of centrality is slightly less than the suppression seen at SPS energies by the NA50 Collaboration, where the "comover" dissociation is substantial and the backward channels play no role. Furthermore, even in the case that all directly produced J/Psi mesons dissociate immediately (or are not formed as a mesonic state), a sizable amount of charmonia is found asymptotically due to the D+(D) over bar -->J/Psi + meson channels in central collisions of Au+Au at roots=200 GeV, which, however, is lower than the J/Psi yield expected from binary scaling of pp collisions.