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 $\frac{m}{g}$ are found. Expansions about the Ising-type vacuum corresponding to large $\frac{m}{g}$ are carried out to order $\frac{1}{g^8{a}^8}$ ($a=\mathrm{lattice}\mathrm{spacing}$) 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 $\frac{1}{g^4{a}^4}$ about the Heisenberg antiferromagnetlike vacuum corresponding to small $\frac{m}{g}$ agree qualitatively with known results for the strong-coupling limit of the continuum theory.