Critical Properties of an Integrable Supersymmetric Eletronic Model

We investigate the physical properties of an integrable extension of the Hubbard model with a free parameter $\gamma$ related to the quantum deformation of the superalgebra $sl(2|2)^{(2)}$. The Bethe ansatz solution is used to determine the nature of the spin and charge excitations. The dispersion relation of the charge branch is given by a peculiar product between energy-momenta functions exhibiting massless and massive behaviors. The study of the finite-size corrections to the spectrum reveals us that the underlying conformal theory has central charge $c=-1$ and critical exponents depending on the parameter $\gamma$. We note that exact results at the isotropic point $\gamma=0$ can be established without recourse to the Bethe ansatz solution.