Superfield derivation of the low-energy effective theory of softly broken supersymmetry

We analyze the soft supersymmetry breaking parameters obtained in grand unified theories after integrating out the heavy GUT-states. The superfield formalism greatly simplifies the calculations and allows us to derive the low-energy effective theory in the general case of non-universal and non-proportional soft terms by means of a few Feynman diagrams. We find new contributions not considered before. We discuss the implications for the destabilization of the gauge hierarchy, flavor violating processes and the non-unification of sparticle masses in unified theories.