QUASI-PARTICLE LIFETIME BEHAVIOR IN A SIMPLIFIED SELF-CONSISTENT T-MATRIX TREATMENT OF THE ATTRACTIVE HUBBARD-MODEL IN 2D

The attractive Hubbard model on a 2D square lattice is studied at low electronic densities using the ladder approximation for the pair susce ptibility. This model includes (i) the short coherence lengths known t o exist experimentally in the cuprate superconductors, and (ii) two-pa rticle bound states that correspond to electron pairs. We study the qu asiparticle lifetimes in both non-self-consistent and self-consistent theories, the latter including interactions between the pairs. We find that if we include the interactions between pairs the quasiparticle l ifetimes vary approximately linearly with the inverse temperature, con sistent with experiment. (C) 1998 Elsevier Science B.V. All rights res erved.