Tc and Pseudogap in the 2D Attractive Hubbard Model

In the fully self-consistent T-matrix formulation, which includes pair fluctuations for T greater than or equal to Tc in a natural way, we have evaluated the critical temperature Tc by studying the divergence of the real part of the T-matrix at omega = 0 and q=0 (Thouless criterion). Moreover, we found strong evidence of the appearance of a pseudogap in the density of states, N(omega), around the chemical potential, mu, with reduced temperature. Our calculations are carried out for the case in which correlations are important, i.e., U/t = -4.0$. The pseudogap is
consistent with numerical and analytical calculations and shows that correlations for T greater than or equal to Tc have important consequences on the density of states.