title: Superconducting gap in the hubbard model and the two-gap energy scales of high-T{c} cuprate superconductors.
abstract: Recent experiments (angle-resolved photoemission spectroscopy and Raman) suggest the presence of two distinct energy gaps in high-temperature superconductors (HTSC), exhibiting different doping dependences. The results of a variational cluster approach to the superconducting state of the two-dimensional Hubbard model are presented which show that this model qualitatively describes this gap dichotomy. The antinodal gap increases with less doping, a behavior long considered as reflecting the general gap behavior of the HTSC. On the other hand, the near-nodal gap does even slightly decrease with underdoping. An explanation of this unexpected behavior is given which emphasizes the crucial role of spin fluctuations in the pairing mechanism.
authors.affiliation: Institute for Theoretical Physics and Astrophysics, University of Würzburg, Am Hubland, 97074 Würzburg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Aichhorn
authors.forename: E
authors.initials: E
authors.lastname: Arrigoni
authors.forename: Z B
authors.initials: ZB
authors.lastname: Huang
authors.forename: W
authors.initials: W
authors.lastname: Hanke