New solutions of the T-matrix theory of the attractive Hubbard model

We present a novel solution method with which we obtain the spectral functi ons of the attractive Hubbard model in two dimensions in a non self-consist ent formulation of the T-matrix approximation. We use a partial fraction de composition of the self energy from which we obtain the single-particle spe ctral functions to a remarkably high accuracy. Here we find the poles and r esidues of the self energy to a relative accuracy of 10(-80) for an 8 x 8 l attice, and plot the resulting density of states. Our results show pseudoga p physics as T-c is approached from above; these analytical results are in agreement with recent Quantum Monte Carlo data.