ON GAUGINO CONDENSATION WITH FIELD-DEPENDENT GAUGE COUPLINGS

We study in detail gaugino condensation in globally and locally supers ymmetric Yang-Mills theories. We focus on models for which gauge-neutr al matter couples to the gauge bosons only through nonminimal gauge ki netic terms, for the cases of one and several condensing gauge groups. Using only symmetry arguments, the low-energy expansion, and general properties of supersymmetry, we compute the low energy Wilson action, as well as the (2PI) effective action for the composite classical supe rfield U=[Tr (WWproportional to)-W-proportional to], with W-proportion al to the supersymmetric gauge field strength. The 2PI effective actio n provides a firmer foundation for the approach of Veneziano and Yanki elowicz, who treated the composite superfield, U, as a quantum degree of freedom. We show how to rederive the Wilson action by minimizing th e 2PI action with respect to U. We determine, in both formulations and for global and local supersymmetry, the effective superpotential, W, the non-perturbative contributions to the low-energy Kahler potential, K, and the leading higher supercovariant derivative terms in an expan sion in inverse powers of the condensation scale. As an application of our results we include the string moduli dependence of the super- and Kahler-potentials for simple orbifold models. (C) 1996 Academic Press , Inc.