Large-distance behaviour of supersymmetric QCD and the instanton vacuum

Instanton-anti-instanton interactions in supersymmetric QCD turn out to be of the long-range Coulomb type. It is shown that infrared divergences disappear when the contributions of all interacting multi-instantons and anti-multi-instantons are summed. The latter summation is done by constructing an effective supersymmetric field theory equivalent to the system of interacting instantons. Certain correlation functions at large distances are calculated by means of this effective field theory. In particular, a non-zero coupling of the current Trλλ to the quasi-Goldstone matter state is shown to be induced by instantons. The absence of a phase boundary between strong and weak coupling phases (complementarity) is also discussed.