Λ⁰-Nucleon Potential and the Binding of Hyperfragments

The volume integral Ω of the effective interaction potential between the Λ hyperon and the nucleon has been calculated from the observed binding energies of hyperfragments of mass number 3, 4, 5, 7, and 9. An assumption of short-range, central, spin-independent forces leads to a single value of Ω=(240±20)×10^-39 Mev cm³, independent of experimental uncertainties in the size and shape of nuclei and in the observed binding energies, except for the case of _ΛHe⁵. The additional freedom gained by assuming central spin-dependent forces does not permit the fitting of _ΛHe⁵ and the other hypernuclei. It is concluded that the explanation of the anomalously low value of Ω for _ΛHe⁵ is to be found in the nuclear properties of its alpha-particle core.