THE NN-]NN-ETA REACTION CLOSE TO THRESHOLD

The pp --> pp eta and np --> np eta reactions at energies near the eta production threshold are studied in a non-relativistic one boson exch ange model, where the N (1535 MeV) S11 resonance is excited through t he exchange of pi, eta, rho and omega mesons and subsequently decays i nto an eta N pair. Energy integrated cross sections and energy spectra of the out going eta's are reported. Providing NN and eta N final sta te interactions are taken into account coherently, the model reproduce s both the scale and energy dependence of the cross section for the pp --> pp eta reactions up to 100 MeV. Final state interaction correctio ns due to the nucleon-nucleon and meson-nucleon forces influence stron gly the scale and shape of the cross sections. The shape of the energy spectra of the outgoing eta's provides a clear signature of the eta N force.