  The attractive Hubbard model on a 2-D square lattice is studied at low
electronic densities using the ladder approximation for the pair
susceptibility. This model includes (i) the short coherence lengths known to
exist experimentally in the cuprate superconductors, and (ii) two-particle
bound states that correspond to electron pairs. We study the quasiparticle
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 lifetimes vary approximately
linearly with the inverse temperature, consistent with experiment.
