FROM BCS-LIKE SUPERCONDUCTIVITY TO CONDENSATION OF LOCAL PAIRS - A NUMERICAL STUDY OF THE ATTRACTIVE HUBBARD-MODEL

We investigate the band structure of the 2D attractive Hubbard model w ith quantum Monte Carlo techniques and the maximum entropy method for analytic continuation. Our interest focuses on intermediate coupling s trengths (about the size of the bandwidth) and on temperatures down to the superconducting transition. In the normal state the band structur e splits from a single band at very high temperatures into a double ba nd structure, with a third feature above T-c. These results are partia lly confirmed by other approximative techniques.