Gaugino masses from radiative corrections in superstring models

We discuss contributions to the observable gaugino masses due to one-loop radiative corrections in the effective theory below the compactification and condensation scales of superstring models. We assume that some unspecified dynamics determines the compactification radius, and that gaugino condensation in the hidden sector generates a gravitino mass smaller than the Planck mass. The largest contribution to the gaugino mass arises from radiative corrections to the effective scalar potential. Scalar masses appear in higher orders of perturbation theory. We comment on the implications for phenomenological model calculations. (orig./HSI)