Meson-exchange hyperon-nucleon interactions in free scattering and nuclear matter

Abstract

Hyperon-nucleon interaction models à and B̃ are presented, in which the explicit energy-dependence of the original models A, B of the Jülich group is removed in order to simplify the application in nuclear structure calculations. As a byproduct we find that the SU (3) parameters like F (F + D) ratios, if obtained by a fit to the hyperon-nucleon scattering data, do depend on the specific model used and on approximations applied. While all models provide a reasonable description of the scarce cross-section data, sizeable differences occur in the, so far unmeasured, spin observables, especially between our models and the models of the Nijmegen group. A measurement of such spin observables should easily discriminate between present models and thus shed some light on various aspects of hyperon-nucleon interactions like e.g. the proper choice of parameter constraints. In a conventional first-order Brueckner calculation based on the standard choice of single-panicle potentials, the binding energy B Λ (∞) of a Λ hyperon in nuclear matter was found to be 29.8 MeV (31.1 MeV) for model à (B̃).