Spectral Properties of the Attractive Hubbard Model
  Deviations from Fermi liquid behavior are well documented in the normal state of the cuprate superconductors, and some of these differences are possibly related to pre-formed pairs appearing at temperatures above T_c. In order to test these ideas we have investigated the attractive Hubbard model within a self-consistent, conserving ladder approximation. In this version of the theory, no feature is present which can be related to the pseudo gap found in the high-T_c materials. Further, the interactions between two-particle bound states change the physics of the superconducting instability in a profound fashion, and lead to a completely different phenomenology that one predicts based on the non-self-consistent version of the same theory. 
M. Letz, R.J. Gooding