Charm Meson Production from Meson-nucleon Scattering

Because of their large masses, one expects charm mesons to be mostly produced in the initial preequilibrium stage of relativistic heavy ion collisions. They have thus been suggested as possible probes of the initial dynamics in these collisions. Previous studies have been concentrated on the production of charm quarks from the preequilibrium partonic matter [1]. For charm meson production from nonpartonic matter, the only study is the one [2] based on the Hadron-String Dynamics (HSD) [3] using hadronic cross sections obtained from the Quark-Gluon String Model (QGSM). The QGSM model treats charm meson production from pion-nucleon scattering as a process involving the exchange of the vector charm meson Regge trajectory in t-channel. Contributions from the s and u channels are neglected. To check the validity of this approximation, we have used an effective hadronic Lagrangian based on the flavor SU(4) symmetry but with empirical hadron masses [4]. The coupling constants are taken, if possible, from empirical information. Otherwise, the SU(4) relations are used to relate the unknown coupling constants to the known ones. This Lagrangian has recently been used to study the cross sections for both absorption [5] and charm meson scattering [6] by hadrons. / J ψ