Dyson treatment of NFT medium polarization processes in superfluid nuclei

We discuss the solution of the Dyson equation (also known as the Nambu-Gor'kov equation) for the case of medium polarization Nuclear Field Theory (NFT) processes in nuclei, and apply it to the nucleus 120Sn. Starting from a mean field obtained with the Sly4 effective nucleon-nucleon force, (mk = 0.7), we renormalize the single-particle states and the pairing interaction through the coupling to collective vibrations of the system, obtaining a detailed description of the fragmentation of the quasiparticle strength and of the state-dependent pairing gap. These quantities are calculated in term of one- and two-particle spectroscopic amplitudes, amplitudes which can be used to calculate both one- and two-nucleon absolute transfer reaction cross sections to be directly confronted with the experimental findings.