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arXiv · 1105.4428

Manifestation of the Upper Hubbard band in the 2D Hubbard model at low electron density

M. Yu. Kagan·V. V. Val'kov·P. Woelfle
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Abstract

We consider the 2D Hubbard model in the strong-coupling case (U>>W) and at low electron density (nd^2<<1). We find an antibound state as a pole in the two-particle T-matrix. The contribution of this pole in the self-energy reproduces a two-pole structure in the dressed one-particle Green-function similar to the Hubbard-I approximation. We also discuss briefly the Engelbrecht-Randeria mode which corresponds to the pairing of two holes below the bottom of the band for U>>W and low electron density. Both poles produce non-trivial corrections to Landau Fermi-liquid picture already at low electron density but do not destroy it in 2D

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M. Yu. Kagan, V. V. Val'kov, P. Woelfle. 2011-05-23. Manifestation of the Upper Hubbard band in the 2D Hubbard model at low electron density. https://doi.org/10.1063/1.3670026

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