SPECTRUM OF LOW-LYING EXCITATIONS IN A SUPERSYMMETRIC EXTENDED HUBBARD-MODEL

We continue the study of the u(2\2)-supersymmetric extension of the Hu bbard model in one dimension. We determine the excitation spectrum at zero temperature even in the sectors where the ground states are u(2\2 )-descendants of Bethe states. The excitations include spinons, holons , electrons, localons (local electron pairs, moving coherently through the lattice) and their bound states. The spectra are found to be very different for repulsive and attractive on-site interaction. We also s tudy the thermodynamics of the model.