Elastic proton scattering on tritium below the $n\text{−}{}^3\mathrm{He}$ threshold

Elastic proton scattering on the ${}^3\mathrm{H}$ nucleus is studied between $p\text{−}{}^3\mathrm{H}$ and $n\text{−}{}^3\mathrm{He}$ thresholds, in the energy region where the first excited state of the $\alpha$ particle is embedded in the continuum. Faddeev-Yakubovski equations are solved in configuration space by fully considering effects from isospin breaking and rigorously treating the Coulomb interaction. Different realistic nuclear Hamiltonians are tested, elucidating open problems in the description of the nuclear interaction.

Figure 1

The experimental spectra of $4N$ bound and resonant states, as obtained using $R$-matrix analysis [9]. Resonances are indicated by the dashed lines. In the right pane of the figure the structure of ${}^4\mathrm{He}$ is elucidated.

Figure 2

Various model calculations for the $p\text{−}{}^3\mathrm{H}$ excitation function ${\frac{d\sigma }{d\Omega }(E)|}_{{\theta }_{\mathrm{c}.\mathrm{m}.}={120}^{°}}$ compared with experimental data from Refs. [25, 26, 27].

Figure 3

Calculated $p\text{−}{}^3\mathrm{H}$ differential cross sections compared with experimental data of Ref. [28] for incident proton energies of 0.3 MeV (left pane) and 0.9 MeV (right pane). If at 0.3 MeV the contribution of $P$ waves is negligible, they are necessary at 0.9 MeV to reproduce bending in the experimental curve. However, if $S$-wave contributions to the elastic scattering cross section differ from model to model at 0.3 MeV, they merge into the same curve at 0.9 MeV.