Search for Deviations from Fermi Liquid Behavior in 2D Repulsive and Attractive Hubbard Models
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We review two very different approaches to the problem of the breakdown of Fermi liquid theory (FLT) in 2D Fermi systems. (I) First we discuss the repulsive Hubbard model. A low density expansion is shown to yield unexpected non-perturbative bound state formation, and yet FLT is robust in this regime. We also briefly review other calculations which address similar issues. (II) Next we turn to the attractive Hubbard model above its superconducting T c . With increasing attraction the normal state is shown to deviate from a Fermi liquid with pseudo-gaps in the charge and spin excitation spectrum.
KeywordsHubbard Model Fermi Liquid Luttinger Liquid Fermi Liquid Theory Fermi Liquid Behavior
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