The differential cross section for the reaction $p{d}^3\mathrm{He}\eta$ in the energy region 930–1100 MeV is investigated in a two-step model. The model assumes a $\pi$ meson to be produced in a first $N\overrightarrow{N}\pi d$ collision and the $\eta$ meson in a second $\pi \overrightarrow{N}\eta N$ collision. Part of the angular dependence observed is ascribed to the $\pi \overrightarrow{N}\eta N$ amplitude, through its dependence on the $P_{11}$ and $D_{13}$ resonances, but the main structure comes from the ${}^3\mathrm{He}$ form factor. Fermi motion is taken into account, but does not seem to significantly change the results. The two-step model by itself is not completely successful in explaining the $p{d}^3\mathrm{He}\eta$ differential cross section, but basic features are reproduced.

• Received 7 January 2003

DOI:https://doi.org/10.1103/PhysRevC.67.034906