The massive Thirring-Schwinger model (QED2): convergence of perturbation theory and particle structure

The equivalence of the massive Thirring-Schwinger model in two space-time dimensions (QED2) on the charge-0-sector and the 'sine-Gordon' theory with a bare mass proportional to the electric charge is reconsidered and rigorously derived from a more general equivalence theorem. It is then shown that for sufficiently large electric charge the Feynman perturbation expansion of the Euclidean Green's functions in the Fermion mass M about M=O converges. Existence of one particle states (Fermion-anti-Fermion bound states) and nontriviality of the S-matrix are proven. The dependence of the scattering matrix on the charges at infinity is analyzed. (Auth.)