GAUGINO CONDENSATION, S-DUALITY AND SUPERSYMMETRY BREAKING IN SUPERGRAVITY MODELS

The status of the gaugino condensation as the source of supersymmetry breaking is reexamined. It is argued that one cannot have stable minim a with broken supersymmetry in models where the dilaton is coupled onl y linearly to the gaugino condensate. We show that the problems of the gaugino condensate mechanism can be solved by considering non-standar d gauge kinetic functions, created by non-perturbative effects, As an example we use the principle of S-duality to modify the coupling of th e gaugino condensate to effective supergravity (superstring) Lagrangia ns. We show that such an approach can solve the problem of the runaway dilaton and lead to satisfactory supersymmetry breaking in models wit h a single gaugino condensate. We exhibit a general property of theori es containing a symmetry acting on the dilaton and also shed some ligh t on the question whether it is generically the auxiliary field of the modulus T that dominates supersymmetry breaking.