${}^3\mathrm{He}$ structure and mechanisms of $p{}^3\mathrm{He}$ backward elastic scattering

The mechanism of $p{}^3\mathrm{He}$ backward elastic scattering is studied. It is found that the triangle diagrams with the subprocesses $p{d}^3\mathrm{He}{\pi }^0,$ ${\overrightarrow{{\mathrm{pd}}^{*}}}^3\mathrm{He}{\pi }^0,$ and ${p\left(\mathrm{pp}\right)\mathrm{}}^3\mathrm{He}{\pi }^{+},$ where $d^{*}$ and $\mathrm{pp}$ denote the singlet deuteron and diproton pair in the ${}^1{S}_0$ state, respectively, dominate in the cross section at 0.3–0.8 GeV, and their contribution is comparable with that for a sequential transfer of a $\mathrm{np}$ pair at 1–1.5 GeV. The contribution of the $d^{*}+pp,$ estimated on the basis of the spectator mechanism of the ${p\left(\mathrm{NN}\right)\mathrm{}}^3\mathrm{He}\pi$ reaction, increases the $p{}^3{\overrightarrow{\mathrm{He}}}^3\mathrm{He}p$ cross section by one order of magnitude as compared to the contribution of the deuteron alone. Effects of the initial and final states’ interaction are taken into account.