Microscopic calculations of Λ single-particle energies

Lambda binding energy data for total baryon number A less than or equal to 208 and for Lambda angular momenta l(Lambda) less than or equal to 3 are analyzed in terms of phenomenological (but generally consistent with meson-exchange) Lambda Nu and Lambda Nu Nu potentials. The Fermi hypernetted chain technique is used to calculate the expectation values for the Lambda binding tonuclear matter. Accurate effective Lambda Nu and Lambda Nu potentials are obtained which are folded with the core-nucleus nucleon densities to calculate the Lambda single-particle potential U-Lambda (r). We use a dispersive Lambda Nu Nu potential but also include an explicit rho dependence to allow for reduced repulsion in the surface, and the best fits have a large rho dependence giving consistency with the variational Monte Carlo calculations for He-5(Lambda). The exchange fraction of the Lambda Nu space-exchange potential is found to be 0.2-0.3 corresponding to m(Lambda)(*) similar or equal to (0.74 - 0.82)m(Lambda). Charge-symmetry breaking is found to be significant for heavy hypernuclei with a large neutron excess, with a strength consistent with that obtained from the A = 4 hypernuclei.