Chiral condensate, master field and all that in QCD2 (N → ∞)

We discuss the various aspects of two-dimensional QCD2 (N → ∞) (the ʹt Hooft model). Our main interest (motivated by the corresponding analysis in the four-dimensional QCD) is the vacuum structure of the theory. We use very general methods in the analysis, such as dispersion relations and duality, in order to relate the known spectrum of QCD2 to the different vacuum characteristics. We explicitly calculate (in terms of physical parameters like masses and matrix elements) the chiral condensate as well as the mixed vacuum condensates: (0|q(gϵμνGμν)nq|0) ∼ Meff2n(0|qq|0). We interpret the factorization property for the mixed vacuum condensates as a reminiscent of the master field at large N.