A microscopic calculation of near-threshold η-meson production in the reaction $N\overrightarrow{N}\mathrm{NN}\eta$ is presented. It is assumed that the η meson is produced via direct emission and via elementary rescattering processes $M\overrightarrow{N}\eta N$ of various mesons $M=\pi ,\rho ,$ etc. As a novel feature the amplitudes for the latter production mechanism are taken from a multichannel meson-exchange model of the $\pi N$ system developed by the Jülich group which contains explicitly the channels $\pi N,\rho N,\eta N,\sigma N,$ and πΔ. Furthermore, effects of the $\mathrm{NN}$ interaction in the final as well as in the initial state are taken into account microscopically. Our results are compared with recent data from the COSY and CELSIUS accelerator facilities. Reasonable agreement with available near-threshold cross section data for the reactions $p\overrightarrow{p}\mathrm{pp}\eta ,p\overrightarrow{n}\mathrm{pn}\eta ,$ and $p\overrightarrow{n}d\eta$ is found.

• Received 4 December 2002

DOI:https://doi.org/10.1103/PhysRevC.67.024002