title: Fluctuation Diagnostics of the Electron Self-Energy: Origin of the Pseudogap Physics.
abstract: We demonstrate how to identify which physical processes dominate the low-energy spectral functions of correlated electron systems. We obtain an unambiguous classification through an analysis of the equation of motion for the electron self-energy in its charge, spin, and particle-particle representations. Our procedure is then employed to clarify the controversial physics responsible for the appearance of the pseudogap in correlated systems. We illustrate our method by examining the attractive and repulsive Hubbard model in two dimensions. In the latter, spin fluctuations are identified as the origin of the pseudogap, and we also explain why d-wave pairing fluctuations play a marginal role in suppressing the low-energy spectral weight, independent of their actual strength.
authors.affiliation: Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, D-70569 Stuttgart, Germany.
authors.forename: O
authors.initials: O
authors.lastname: Gunnarsson
authors.affiliation: Institute of Solid State Physics, Vienna University of Technology, A-1040 Vienna, Austria.
authors.forename: T
authors.initials: T
authors.lastname: Schäfer
authors.affiliation: Max-Planck-Institute for the Physics of Complex Systems, D-01187 Dresden, Germany.|Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: J P F
authors.initials: JP
authors.lastname: LeBlanc
authors.affiliation: Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: E
authors.initials: E
authors.lastname: Gull
authors.affiliation: Departamento de Física Teórica de la Materia Condensada, IFIMAC Universidad Autónoma de Madrid, Madrid 28049, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Merino
authors.affiliation: Institute of Physics and Astrophysics, University of Würzburg, D-97070 Würzburg, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Sangiovanni
authors.affiliation: Institute of Solid State Physics, Vienna University of Technology, A-1040 Vienna, Austria.
authors.forename: G
authors.initials: G
authors.lastname: Rohringer
authors.affiliation: Institute of Solid State Physics, Vienna University of Technology, A-1040 Vienna, Austria.
authors.forename: A
authors.initials: A
authors.lastname: Toschi