η- and η′-meson production in the reaction pn→dM near threshold

The two-step model with π, ρ and ω exchanges taken into account is applied to investigate the reactions pn→dη and pn→dη′ near the corresponding thresholds. The existing experimental data on the reaction pn→dη are analyzed and predictions for the cross section of the reaction pn→dη′ are presented. It is found that π- as well as ρ-meson exchanges yield significant contributions in both reactions. Furthermore, the effect of the ηd final-state interaction is studied. It is shown that an ηN-scattering length of Re aηN≤0.3 fm might be sufficient to reproduce the observed enhancement of the pn→dη cross section close to threshold.