ON THE UNIVERSAL BUNDLE FOR GRAVITY

We construct a supergravity type theory based on a superspace whose odd directions consist of a vector, together with a scalar representing a topological BRST shift symmetry. As such, the resulting theory is a theory of topological gravity. The gravitino is interpreted as a ghost field for this shift symmetry and plays the usual role of gauge field for local supersymmetry. Our construction is within the bundle of frames approach to superspace where covariant torsion constraints are analyzed, and we find that the resulting theory contains additional fields which are not present in existing theories of topological gravity. In particular, a minimal solution exists which contains a BRST invariant scalar field. Vector supergravity presents a field theoretic model of a universal bundle for gravity, and we show how the vector supersymmetry operator can be used to generate a hierachy of observables.