The ηNN-system at low energy within a three-body approach Original Research Article

The role of the ηNN interaction is studied in the low-energy regime in η–deuteron reactions as well as in coherent and incoherent η photoproduction on the deuteron using a three-body model with separable two-body interactions. The three-body approach turns out to be quite essential in the most important lowest partial wave. Results are presented for differential and total cross sections as well as for the η-meson spectrum. They differ significantly from those predicted by a simple rescattering model in which only first-order ηN and NN interactions in the final state are considered. The major features of the experimental data of η photoproduction in the near-threshold region are well reproduced.