The electromagnetic and weak neutral current matrix elements that enter in the analysis of parity-violating quasielastic electron scattering are calculated using a continuum nuclear shell model. New approximations to the on-shell relativistic one-body currents and relativistic kinematics for use in such models are developed and discussed in detail. Results are presented for three closed-shell nuclei of interest: 16 O, 40 Ca and 208 Pb. The current work concludes with a study of the sensitivity of the resulting parity-violating asymmetries to properties of the nucleon form factors including the possible strangeness content of the nucleon.

Abslraci The magnetic excited states of "Ca below panicle emission threshold (i.e. up to N 10 MeV) are studied in the framework of the random-phase approximation.The mulls of the calculation are compared with the available experimental data. The obtained wavefunctions are analysed by calculating lhe iorm factors corresponding to the excitation of the different states by means of inelastic electron scatlering. In particular, the role of the non-dominant one-particle-me-hole components of the RPA wavefunctions is investigated. Special attention is paid to the exciution energy region berween 6 and 8 MeV because of ils particular characteristics regarding the details of the residual nucleon-nucleon interaction.

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We discuss the need of including tensor terms in the effective Gogny interaction used in meanfield calculations. We show in one illustrative case that, with the usual tensor term that is employed in the Skyrme interaction (and that allows us to separate the like-nucleon and the neutron-proton tensor contributions), we can describe the evolution of the N = 28 neutron gap in calcium isotopes.We propose to include a tensor and a tensor-isospin term in finite-range interactions of Gogny type. The parameters of the two tensor terms allow us to treat separately the like-nucleon and the neutron-proton contributions. Two parameterizations of the tensor terms have been chosen to reproduce different neutron single-particle properties in the 48 Ca nucleus and the energy of the first 0 − state in the 16 O nucleus. By employing these two parameterizations we analyze the evolution of the N = 14, 28, and 90 neutron energy gaps in oxygen, calcium and tin isotopes, respectively.We show that the combination of the parameters governing the like-nucleon contribution is crucial to correctly reproduce the experimental (where available) or shell-model trends for the evolution of the three neutron gaps under study.

A model to calculate nuclear responses considering short-range correlation effects is presented. The model is applied to the study of electromagnetic responses induced by one-body operators. We calculate one-and two-nucleon emission responses and cross sections of the 16 O and 40 Ca nuclei in the quasi-elastic region, and we compare them with experimental data. Academic Press