T-DUALITY AND SPACE-TIME SUPERSYMMETRY

We analyze in detail the possible breaking of space-time supersymmetry under T-duality transformations. We find that when appropriate world- sheet effects are taken into account apparent puzzles concerning super symmetry in space-time are solved. We study T-duality in general heter otic sigma-models analyzing possible anomalies, and we find some modif ications of Buscher's rules. We then work out a simple but representat ive example which contains most of the difficulties. We also consider the issue of supersymmetry versus duality for marginal deformations of WZW models and present a mechanism that restores supersymmetry dynami cally in the effective theory.