A functional approach to the many-body nuclear problem: the MEC

Summary We show how a functional approach to the nuclear many-body problem can provide a unified scheme to deal with the many facets of the problem and to establish well-defined procedures of approximation. We consider, in particular, the perturbative and the mean-field (loop expansion) approximations to an exact effective bosonic Lagrangian, discussing how well-known computational schemes (hole-line expansion, RPA, etc.) may be obtained as subsets of definite orders in these expansions. An application to the calculation of the longitudinal electromagnetic response function, with the simpleNπ interaction, is finally presented. We show how the pion dynamic and the short-range correlations cooperate to obtain a better agreement with experimental data. Presented by R. Cenni.