SOLITONS, TAU-FUNCTIONS AND HAMILTONIAN REDUCTION FOR NON-ABELIAN CONFORMAL AFFINE TODA THEORIES

We consider the Hamiltonian reduction of the ''two-loop'' Wess-Zumino- Novikov-Witten model (WZNW) based on an untwisted affine Kac-Moody alg ebra G. The resulting reduced models, called Generalized Non-Abelian C onformal Affine Toda (G-CAT), are conformally invariant and a wide cla ss of them possesses soliton solutions; these models constitute non-Ab elian generalizations of the conformal affine Toda models. Their gener al solution is constructed by the Leznov-Saveliev method. Moreover, th e dressing transformations leading to the solutions in the orbit of th e vacuum are considered in detail, as well as the tau-functions, which are defined for any integrable highest weight representation of G, ir respectively of its particular realization. When the conformal symmetr y is spontaneously broken, the G-CAT model becomes a generalized affin e Toda model, whose soliton solutions are constructed, Their masses ar e obtained exploring the spontaneous breakdown of the conformal symmet ry, and their relation to the fundamental particle masses is discussed . We also introduce what we call the two-loop Virasoro algebra, descri bing extended symmetries of the two-loop WZNW models.