Ground State Correlations and Final State Interactions in Two-nucleon Emission Processes off Few-nucleon Systems

The investigation of Ground State Correlations (GSC) in nuclei, in particular those which originate from the most peculiar features of the Nucleon-Nucleon (NN) interaction, i.e. its strong short range repulsion and complex state dependence (spin, isospin, tensor, etc), is one of the most challenging aspects of experimental and theoretical nuclear physics and, more generally, of hadronic physics. The results of sophisticated many-body calculations in terms of realistic models of the NN interactions, show that the complex structure of the latter generates a rich correlation structure of the nuclear ground state wave function. The experimental investigation of the nuclear wave function or, better, of various density matrices, ρ(1), ρ(1, 1), ρ(1, 2), etc , is therefore necessary in order to ascertain whether the prediction of the Standard Model of nuclei (structureless nonrelativistic nucleons interacting via the free NN interaction) is indeed justified in practice, or other phenomena, e.g.: