The $ηNN$-system at low energy within a three-body approach

Abstract

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.

20 pages revtex including 10 figures, revised version accepted for publication in Nucl. Phys. A