ANALYTIC BETHE-ANSATZ FOR 1D HUBBARD-MODEL AND TWISTED COUPLED XY MODEL

We have found the eigenvalues of the transfer matrices for the 1D Hubb ard model and for the coupled XY model with a twisted boundary conditi on by using the analytic Bethe ansatz method. Under a particular condi tion the two models have the same Bethe ansatz equations. We have also proved that the periodic 1D Hubbard model is exactly equal to the cou pled XY model with a non-trivial twisted boundary condition at the lev el of Hamiltonians and transfer matrices.