ETA-PRODUCTION IN PROTON-NUCLEUS REACTIONS

The production of eta-mesons in proton-nucleus reactions is analysed with respect to primary nucleon-nucleon (NN --> NN-eta) and secondary pion-nucleon (pi-N --> eta-N) production processes on the basis of Hartree-Fock groundstate momentum distributions and free on-shell production processes. The folding model adopted compares well for meson production with more involved simulations based on VUU transport equations. Similar to K+ production in proton-nucleus reactions the eta-mesons are primarily produced by the pi-N --> eta-N channel. However, eta-mesons are absorbed in nuclei via excitation of the N*(1535) resonance which leads to strong distortions of the primordial spectra. On the other hand, the experimental mass dependence of the differential cross sections might yield information about the in-medium properties of this resonance.