The usefulness of the three-body mechanism of $\eta$-meson production is tested by extending to high energies a recently developed two-step model of the $pd\to {}^3\mathrm{He}\eta$ reaction by us, which was successful in reproducing the energy dependence of the data near threshold. The $\eta$ production in this model proceeds in two steps via the $pp\to \pi d$ and $\pi N\to \eta p$ reactions with the intermediate particles being off-shell. The final state interaction is incorporated through a $T$ matrix for $\eta {}^3\mathrm{He}$ elastic scattering constructed using few body equations. In a comparison of the calculated angular distributions with some recently available data, we discover the limitations of the model at high energies.

• Received 4 September 2003

DOI:https://doi.org/10.1103/PhysRevC.68.064610