Quantum effects and SU(2)×U(1) breaking in supergravity gauge theories

Renormalization effects are studied at the one-loop level in the context of gauge models coupled to supergravity. General renormalization group equations are derived for the parameters of the effective theory by taking advantage of the supersymmetric structure. One-loop gaugino masses, which enter these equations are calculated in grand unified models and turn out to be rather large. The results are applied to the study of the effective theory of a SU(3)×SU(2)×U(1) model which includes a gauge singlet in addition to the minimal set of fields. It is possible to induce the correct breaking of the electroweak gauge invariance when quantum corrections are taken into account, even without very heavy quarks.