The one-dimensional Hubbard model with arbitrary degeneracy N (N = 2S + 1, where S is the spin) is integrable if site-occupations of more than two electrons are excluded. The Bethe-ansatz equations are analyzed in the thermodynamic limit in the absence of external fields. In the large N limit they reduce to those of a hard core Bose gas. The 1/N-correction to the leading order result vanishes identically, so that the first corrections are contributions of the order 1/N2.
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We would like to acknowledge the support by US Department of Energy under the grant DE-FGOZ 87ER45333.