The role of ground state correlations in the single-particle strength of odd nuclei with pairing

A method based on the consistent use of the Green function formalism has been developed to calculate the distribution of the single-particle strength in odd nuclei with pairing. The method takes into account the quasiparticle-phonon interaction, ground state correlations and a ``refinement'' of phenomenological single-particle energies and pairing gap values from the quasiparticle-phonon interaction under consideration. The calculations for ¹²¹Sn and ¹¹⁹Sn that were performed in the quasiparticle⊗phonon approximation, have shown a reasonable agreement with experiment. The ground state correlations play a noticeable role and mostly improve the agreement with experiment or shift the results to the right direction.