M ay 1 99 8 Hyperon properties in finite nuclei using realistic Y N interactions

Single-particle energies of Λ and Σ hyperons in several nuclei are obtained from the relevant self–energies. The latter are constructed within the framework of a perturbative many-body approach employing present realistic hyperon-nucleon interactions such as the models of the Jülich and Nijmegen groups. The effects of the non-locality and energy-dependence of the self– energy on the bound states are investigated. It is also shown that, although the single-particle hyperon energies are well reproduced by local Woods-Saxon hyperon-nucleus potentials, the wave functions from the non-local self–energy are far more extended. Implications of this behavior on the mesonic weak decay of Λ hypernuclei are discussed.