SEMICLASSICAL SPECTRUM OF THE HOMOGENEOUS SINE-GORDON THEORIES

The semi-classical spectrum of the homogeneous sine-Gordon theories as sociated with an arbitrary compact simple Lie group G is obtained and shown to be entirely given by solitons, These theories describe quantu m integrable massive perturbations of Gepner's G-parafermions whose cl assical equations-of-motion are non-abelian affine Toda equations, One -soliton solutions are constructed by embeddings of the SU(2) complex sine-Gordon soliton in the regular SU(2) subgroups of G. The resulting spectrum exhibits both stable and unstable particles, which is a pecu liar feature shared with the spectrum of monopoles and dyons in N = 2 and N = 4 supersymmetric gauge theories. (C) 1998 Elsevier Science B.V .