Self-energy corrections to the electronic spectrum of the Hubbard model

A new approach to investigate the electronic spectrum of the Hubbard model is presented. The complex dynamics of the composite fields is taken into account self-consistently well beyond the mean-field approximation by means of the composite operator method in the framework of the projection techniques for the Green's functions. Corrections to the bare single-particle spectrum of original fermions are computed applying the self-consistent Born approximation to the self-energy usually neglected in the previously used two-pole approximation. © 2004 Elsevier B.V. All rights reserved.