Extended Becchi-Rouet-Stora invariance for gravity via local OSp(4/2) supersymmetry

The supersymmetry OSp(⁴/₂) provides a natural classification group for gauge fields and their fictitious partners, needed for gauge fixing and restoration of unitarity. When the gravitational field and its adjuncts are so treated, with appropriate geometrical restrictions on the geometry of the superspace, a natural extended Becchi-Rouet-Stora (BRS) symmetry emerges for gravity in which the ghosts appear on an equal footing. The resulting action, invariant under gravitational BRS transformations and their duals, differs from the conventional asymmetric form. The validity of the new BRS identities is verified at the tree and one-loop levels.