Analysis of theΛ−NInteraction

We examine whether the recent low-energy $\Lambda -N$ scattering data of Alexander et al. are compatible with the binding energies of ${}_{\Lambda }{}^{}{}_{}{}^{}\mathrm{H}_{}^3{}_{}{}^{}$ and ${}_{\Lambda }{}^{}{}_{}{}^{}\mathrm{He}_{}^5{}_{}{}^{}$, if only central $\Lambda -N$ forces are assumed. We set up $\Lambda -N$ and $N-N$ potentials, in the spirit of the Moszkowski-Scott separation method, to fit the low-energy scattering parameters. It is found that although these forces are compatible with the ${}_{\Lambda }{}^{}{}_{}{}^{}\mathrm{H}_{}^3{}_{}{}^{}$ binding, ${}_{\Lambda }{}^{}{}_{}{}^{}\mathrm{He}_{}^5{}_{}{}^{}$ is grossly overbound. This is interpreted as an indication for the existence of an appreciable tensor component in the triplet $\Lambda -N$ potential.