ASPECTS OF SPONTANEOUSLY BROKEN N=1 GLOBAL SUPERSYMMETRY IN THE PRESENCE OF GAUGE INTERACTIONS

We discuss models where N = 1 global supersymmetry is spontaneously br oken, at the classical level, in the presence of non-anomalous gauge i nteractions. We take such models as effective theories, valid up to so me suitable scale and arising from supergravity models with a light gr avitino, and therefore we allow them to contain non-renormalizable int eractions. First, we examine the case where the goldstino is a gauge s inglet. We elucidate the model-independent relations between supersymm etry-breaking masses and some associated interactions, with special at tention to the behaviour of some four-particle scattering amplitudes i n the high- and low-energy limits. The former gives constraints from t ree-level unitarity, the latter affects the phenomenological lower bou nds on the gravitino mass. In particular, we give new results for the annihilation of photons into gravitinos, and discuss their implication s. We then examine the case with no neutral chiral superfields, so tha t the goldstino is charged, and the gauge symmetry is also broken. In this context, we discuss the singularity structure and the associated unitarity constraints, relating the scales of supersymmetry and gauge symmetry breaking, We conclude by commenting on possible realistic exa mples, where the broken gauge symmetry is associated with grand or ele ctroweak unification. (C) 1997 Elsevier Science B.V.