Production of \( \eta\) and 3\( \pi\) mesons in the pd \( \rightarrow\) 3HeX reaction at 1360 and 1450 MeV

The cross-sections of the pd \( \rightarrow\) 3He\( \eta\) , pd \( \rightarrow\) 3He \( \pi^{0}_{}\) \( \pi^{0}_{}\) \( \pi^{0}_{}\) and pd \( \rightarrow\) 3He \( \pi^{+}_{}\) \( \pi^{-}_{}\) \( \pi^{0}_{}\) reactions have been measured at the beam kinetic energies T p= 1360 MeV and T p= 1450 MeV using the CELSIUS/WASA detector setup. At both energies, the differential cross-section \(\tfrac{{d\sigma }} {{d\Omega }}\) of the \( \eta\) meson in the pd \( \rightarrow\) 3He\( \eta\) reaction shows a strong forward-backward asymmetry in the CMS. The ratio between the pd \( \rightarrow\) 3He \( \pi^{+}_{}\) \( \pi^{-}_{}\) \( \pi^{0}_{}\) and pd \( \rightarrow\) 3He \( \pi^{0}_{}\) \( \pi^{0}_{}\) \( \pi^{0}_{}\) cross-sections has been analysed in terms of isospin amplitudes. The reconstructed invariant-mass distributions of the \( \pi\) \( \pi\) ,