Near threshold meson production in nucleon-nucleon collisions

A model calculation for pion production in nucleon-nucleon collisions is presented. Direct production, pion re-scattering and contributions from pair diagrams are taken into account. The amplitudes for the elementary processes are based on well established microscopic models of nucleon-nucleon and pion-nucleon scattering. The comparison with experiments focuses on recently measured polarization observables. Furthermore, results of a study of the reaction NN --> NNeta are presented, performed in the same spirit and the same framework as pion production. Reasonable agreement with available near-threshold cross section data for the reactions pp --> ppeta, pn --> pneta, and pn --> deta is found.