Bethe Ansatz and thermodynamic limit of affine quantum group invariant extensions of the t-J model

We have constructed a one-dimensional exactly solvable model, which is base d on the t-J model of strongly correlated electrons, but which has addition al quantum group symmetry, ensuring the degeneration of states. We use Beth e Ansatz technique to investigate this model. The thermodynamic limit of th e model is considered and equations for different density functions written down. These equations demonstrate that the additional color degrees of fre edom of the model behave as in a gauge theory, namely, an arbitrary distrib ution of color indices over particles leave invariant the energy of the gro und state and the excitations. The S-matrix of the model is shown to be the product of the ordinary t-J model S-matrix and the unity matrix in the col or space. (C) 1999 American Institute of Physics. [S0022-2488(99)02411-1].