New super-selection sectors ('soliton-states') in two dimensional bose quantum field models

A rigorous construction of super-selection sectors - so-called 'soliton-sectors' - for the quantum 'sine-Gordon' equation and the (phi*phi)2-quantum field models with explicitly broken isospin symmetry in two space-time dimensions is presented. These sectors are eigenspaces of the charge Q = ∫ dx(grad phi)(x) with non-zero eigenvalue. The scattering theory for quantum solitons is briefly discussed and shown to have consequences for the physics in the vacuum sector. A general theory is developed which explains why soliton-sectors may exist for theories in two but not in four space-time dimensions except possibly for non-abelian Yang-Mills theories. (orig.)