Physical picture of the gapped excitation spectrum of the one-dimensional Hubbard model
arXiv:cond-mat/9809290 · doi:10.1016/S0550-3213(98)00811-6
Abstract
A simple picture for the spectrum of the one-dimensional Hubbard model is presented using a classification of the eigenstates based on an intuitive bound-state Bethe-Ansatz approach. This approach allows us to prove a "string hypothesis" for complex momenta and derive an exact formulation of the Bethe-Ansatz equations including all states. Among other things we show that all gapped eigenstates have the Bethe-Ansatz form, contrary to assertions in the literature. The simplest excitations in the upper Hubbard band are computed: we find an unusual dispersion close to half-filling.
22 pages, revtex, 4 eps-figures