Scattering lengths for p-³He elastic scattering from an effective-range phase shift analysis

We have extended an earlier phase-shift analysis of p-³He scattering data by including additional low-energy measurements in the dataset. The p-³He zero-energy scattering lengths obtained from this analysis depend sensitively on a group of cross section and analyzing power measurements at proton energies below 1 MeV. When this group of measurements is included in the dataset, two possible phase-shift solutions are found. The first solution yields a singlet scattering length of a_s=15.1fm and a triplet scattering length of a_t=7.9fm, while the second solution yields values of a_s=7.2fm and a_t=10.4fm. Without this group of measurements, the best-fit scattering lengths are a_s=10.3fm and a_t=8.2fm. We believe that the scattering lengths are currently not well determined experimentally and that additional low-energy p-³He data are needed in order to clarify the situation.