Preliminary ab-initio applications of many-body Green's functions theory to
the ground state of He-4 suggest that high accuracy can be achieved in the
so-called Faddeev-random-phase-approximation method.
We stress the potentialities of this approach for microscopic studies of
medium-large nuclei and report applications to 1s0d and 1p0f-shell nuclei. In
particular, we discuss the role of long-range correlations on spectroscopic
factors and their dependence on asymmetry.Comment: Minor corrections and references added -- Proceedings of the Varenna
conference, June 15-19, 200
