Microscopic calculations of (lambda) single-particle energies.

摘要

(Lambda) binding energy data for total baryon number A (le) 208 and for (Lambda) angular momenta (ell)(sub (Lambda)) (le) 3 are analyzed in terms of phenomenological (but generally consistent with meson-exchange) (Lambda)N and (Lambda)NN potentials. The Fermi-Hypernetted-Chain technique is used to calculate the expectation values for the (Lambda) binding to nuclear matter. Accurate effective (Lambda)N and (Lambda)NN potentials are obtained which are folded with the core nucleus nucleon densities to calculate the (Lambda) single particle potential U(sub (Lambda))(r). We use a dispersive (Lambda)NN 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 (sub (Lambda))(sup 5)He. The exchange fraction of the (Lambda)N space-exchange potential is found to be 0.2-0.3 corresponding to m(sub (Lambda))* (approx equal) (0.74-0.82)m(sub (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.