SU(2)-flavor Schwinger model on the lattice

Hamiltonian lattice perturbation methods are used to study the (1 + 1)-dimensional, SU(2)-flavor Abelian gauge model. For a model with coupling constant g and fermion mass m, two distinct vacuum regions characterized by the magnitude of mg are found. Expansions about the Ising-type vacuum corresponding to large mg are carried out to order 1g8a8 (a=lattice spacing) and improved using Padé approximants. The results compare favorably qualitatively and quantitatively with recent studies of the weak-coupling limit of the continuum theory. Expansions to order 1g4a4 about the Heisenberg antiferromagnetlike vacuum corresponding to small mg agree qualitatively with known results for the strong-coupling limit of the continuum theory.