Meson Production in Proton-Nucleus and Nucleus-Nucleus Collisions*

The production of K+ or q mesons in proton-nucleus reactions is analysed with respect to primary nucleon-nucleon (NN + NhK+ or NNq) and secondary pion-nucleon (nN + K+A or qN) production channels on the basis of a phase-space model employing Hartree-Fock groundstate momentum distributions and free on-shell production processes. The phasespace model adopted here compares well for meson production with more involved simulations based on VUU transport equations. Whereas for K+ production in proton-nucleus reactions the secondary channel clearly dominates at subthreshold energies, q mesons arise from primary and secondary processes with roughly the same order of magnitude. Detailed VUU calculations show that the relative weight of the various channels for nucleus-nucleus reactions is quite different as compared to the protonnucleus case since A-resonance excitation and inelastic A-nucleon collisions are much more frequent.