Temperature and Interaction Dependence of the Electron Spectrum in a 2D Attractive Hubbard Model

Abstract

We study the temperature and the interaction dependence of Green’s function in the attractive Hubbard model using self-consistent T-matrix approximation (SCTMA). It is found that at low temperatures, the spectrum of electrons on the Fermi surface shows a three-peak structure. On the other hand, at high temperatures, the spectrum has only two peaks. We also find that by increasing the electron–electron attraction, the temperature at which the explained three-peak spectrum appears is decreased. These results are partially explained by the static superconducting fluctuation; however, at strong coupling we need to include the effect of dynamical fluctuation. The “preformed pair” scenario of the pseudogap in high-T_c superconductors and the validity of SCTMA for the BCS–Bose Einstein condensation crossover problem are discussed.