The Massive Schwinger Model - a Hamiltonian Lattice Study in a Fast   Moving Frame
  We present a non-perturbative study of the massive Schwinger model. We use a Hamiltonian approach, based on a momentum lattice corresponding to a fast moving reference frame, and equal time quantization. We present numerical results for the mass spectrum of the vector and scalar particle. We find good agreement with chiral perturbation theory in the strong coupling regime and also with other non-perturbative studies (Hamer et al., Mo and Perry) in the non-relativistic regime. The most important new result is the study of the $\theta$-action, and computation of vector and scalar masses as a function of the $\theta$-angle. We find excellent agreement with chiral perturbation theory. Finally, we give results for the distribution functions. We compare our results with Bergknoff's variational study from the infinite momentum frame in the chiral region. 
Helmut Kr\"oger, Norbert Scheu