Destabilizing the gaugino condensate in modular invariant supergravity

We investigate the stability of the hidden sector gaugino condensate in a S L(2,Z)-invariant supergravity model inspired by E(8)xE(8) heterotic string, using the chiral superfield formalism. We calculate Planck-suppressed corr ections to the "truncated approximation" for the condensate value and scala r potential. A transition to a phase with zero condensate occurs near speci al points in moduli space and at large compactification radius. We discuss the implications for the T-modulus dependence of supersymmetry-breaking. (C ) 1999 Published by Elsevier Science B.V. All rights reserved.