DUALITY IN DEFORMED COSET FERMIONIC MODELS

We study the SU(2)(k)/U(1) parafermion model perturbed by its first th ermal operator, By formulating the theory in terms of a (perturbed) fe rmionic coset model we show that the model is equivalent to interactin g WZW fields module free fields. In this scheme, the order and disorde r operators of the Z(k) parafermion theory are constructed as gauge-in variant composites, We find that the theory presents a duality symmetr y that interchanges the roles of the spin and dual spin operators. For two particular values of the coupling constant we find that the theor y recovers conformal invariance and the gauge symmetry is enlarged. We also find a novel self-dual point.