Single particle properties of 16O and 40Ca

We discuss some single particle properties of $^{16}$O and $^{40}$Ca using correlated basis function theory and Fermi hypernetted chain equations with central and tensor correlations. In particular, we concentrate on one body density matrix, momentum distribution, natural orbits and quasi hole states. The correlations are variationally generated by a realistic hamiltonian containing the Argonne $v'_{8}$ two-nucleon and Urbana IX three-nucleon interactions. The correlated momentum distributions show the well known enhancement at large momenta, with a relative importance of the different correlations (Jastrow and tensor) similar to that in nuclear matter. The natural orbits and their occupation numbers are obtained by diagonalization of the density matrix. The correlated first natural orbits occupations are depleted by more than 10%, whereas the first following ones are occupied by a few percent. The spectroscopic factors of the valence states are lowered by $\sim 8-12$ with respect to unity by central and tensor correlations, confirming that short range correlations alone are not able to explain the values extracted from $(e,e'p)$ experiments.