Λ-Nucleon Potential from Hyperfragment Data

The volume integrals of the $\Lambda$-nucleon potentials in the triplet and singlet spin states are deduced from hyperfragment binding-energy data. The effects of tensor forces are neglected in the calculation but are discussed qualitatively. Results are sensitive to the sizes and shapes of the nuclei in which the $\Lambda$ is bound, but are not very sensitive to $\Lambda$ binding energies. Results also depend on the range of the $\Lambda$-nucleon potential and on the spin configurations of the nuclei. Within the approximations made, the $\Lambda$-nucleon potentials are consistent with experiment and agree with theoretical potentials due to pion exchange. A crude determination of the $\Lambda$-nucleon potential from the observed lifetime for mesonic decay of hyperfragments is consistent with the binding-energy determination.