The Condensate for SU(2) Yang-Mills Theory in 1+1 Dimensions Coupled to Massless Adjoint Fermions

Abstract

We consider SU(2) Yang-Mills theory in 1+1 dimensions coupled to massless adjoint fermions. With all fields in the adjoint representation the gauge group is actually SU(2)/Z_2, which possesses nontrivial topology. In particular, there are two distinct topological sectors and the physical vacuum state has a structure analogous to a \theta vacuum. We show how this feature is realized in light-front quantization, using discretization of x^- as an infrared regulator. We find exact expressions for the vacuum states and construct the analog of the \theta vacuum. We calculate the bilinear condensate of the model. We argue that this condensate does not effect the spectrum of the massless theory but gives the string tenson of the massive theory.