Four-fermion interactions and sgoldstino masses in models with a superlight gravitino

We discuss the role of the effective interactions among four matter fermions in supersymmetric models with a very light gravitino. We show that, from a field-theoretical viewpoint, no model-independent bound on the gravitino mass can be derived from such interactions. Making use of a naturalness criterion, however, we are able to derive some interesting but not very stringent bounds, complementary to those obtained from the direct production of supersymmetric particles