Abstract

ZANDRON, Oscar P.. Non perturbative expansion for the Generalized Hubbard Model. Nova scientia [online]. 2010, vol.2, n.4, pp.77-92. ISSN 2007-0705.

In this paper we extend previous results obtained in the framework of the Lagrangian formalism for the normal-state case to the superconducting state. The non-perturbative expansion applied to the generalized Hubbard model describing N-fold-degenerate correlated bands for large-N is considered. The standard Feynman diagrammatics is obtained and the renormalized physical quantities for this model are computed and analyzed. Our purpose is to obtain the 1/N corrections to the renormalized boson and fermion propagators for a state with Cooper-pair condensation.

Keywords : Lagrangian formalism; Hubbard model; Feynman diagrammatics.