THE SINE-GORDON MODEL AS SO(N)1XSO(N)1/SO(N)2-PERTURBED COSET THEORY AND GENERALIZATIONS

The ground state energies of the SO(2n)1xSO(2n)1/SO(2n)2 coset theories, perturbed by the phi(adj)id,id operator, and those of the sine-Gordon theory, for special values of the coupling constant in the attracting regime, are the same. In the first part of this paper we extend these results to the SO(2n - 1) cases. In the second part, we analyze the algebraic Bethe ansatz procedure for special points in the repulsive region. We find a one-to-one ''duality'' correspondence between these theories and those studied in the first part of the paper. We use the gluing procedure at the massive node proposed by Fendley and Intriligator in order to obtain the TBA systems for the generalized parafermionic supersymmetric sine-Gordon model. In the third part we propose the TBA equations for the whole class of perturbed coset models G(k)xG(l)/G(k+l) with the operator phi(adj)id,id and G a nonsimplylaced group generated by one of the G2, F4, B(n), C(n) algebras.