GAUGINO CONDENSATION, DUALITY AND SUPERSYMMETRY BREAKING

The status of gaugino condensation in low-energy string theory is revi ewed. Emphasis is given to the determination of the efective action be low condensation scale in terms of the 2PI and Wilson actions. We illu strate how the different perturbative duality symmetries survive this simple nonperturbative phenomenon, providing evidence for the believe that these are exact nonperturbative symmetries of string theory. Cons istency with T duality lifts the moduli degeneracy. The B-mu nu - axio n duality also survives in a nontrivial way in which the degree of fre edom corresponding to B-mu nu is replaced by a massive H-mu nu rho fie ld but duality is preserved. S duality may also be implemented in this process. Some general problems of this mechanism are mentioned and th e possible nonperturbative scenarios for supersymmetry breaking in str ing theory are discussed.