Instantons at strong coupling, averaging over vacua, and the gluino condensate Original Research Article

We consider instanton contributions to chiral correlators, such as 〈0|Tr λ2(x)Tr λ2(x′)|0〉, in N=1 supersymmetric Yang–Mills theory with either light adjoint or fundamental matter. Within the former model, extraction of the gluino condensate from a connected 1-instanton diagram, evaluated at strong coupling, can be contrasted with expectations from the Seiberg–Witten solution perturbed to an N=1 vacuum. We observe a numerical discrepancy, coinciding with that observed previously in N=1 SQCD. Moreover, since knowledge of the vacuum structure is complete for softly broken N=2 Yang–Mills, this model serves as a counter example to the hypothesis of Amati et al. that 1-instanton calculations at strong coupling can be interpreted as averaging over vacua. Within N=1 SQCD, we point out that the connected contribution to the relevant correlators actually vanishes in the weakly coupled Higgs phase, despite having a non-zero value through infra-red effects when calculated in the unbroken phase.