Condensates and Vacuum Structure of Adjoint QCD_2

Abstract

We discuss a two dimensional SU(N) Yang-Mills theory coupled to massive adjoint fermions for different worlds classified by the integer k=0,1,...N-1. We study the fermion condensate for these unconnected worlds as a function of the parameter k. We show that the condensate as well as the spectrum of the theory do depend on this vacuum parameter k. Technically, the value of the fermion condensate is related to the value of the gluon condensate via the Operator Product Expansion. We use this to find the leading dependence (in the limit of a heavy quark) of the fermion condensate on the nontrivial vacuum angle k. We also determine the gluon condensate of the theory using low-energy theorems.