The excitation spectrum of the orbitally degenerate Hubbard model in one dimension: Absence of Cooper pairing

The degenerate Hubbard chain with N internal degrees of freedom is integrable if site occupations of more than two electrons are excluded. If on average there is exactly one electron per site, the system is a Mott-Hubbard insulator. The authors discuss the elemental charge and spin excitations, the effects of crystalline fields quenching the orbital degrees of freedom, and the implications of hole states for superconductivity.