UV structure of quantum unimodular gravity

It is a well-known result that any formulation of unimodular gravity is classically equivalent to general relativity (GR); however, a debate exists in the literature about this equivalence at the quantum level. In this work, we investigate the UV quantum structure of a diffeomorphism-invariant formulation of unimodular gravity using functional renormalization group methods in a Wilsonian context. We show that the effective action of the unimodular theory acquires essentially the same form as that of GR in the UV, and that both theories share similar UV completions within the framework of the asymptotic safety scenario for quantum gravity. Furthermore, we find that in this context the unimodular theory can appear to be nonpredictive due to an increasing number of relevant couplings at high energies, and we explain how this unwanted feature is in the end avoided.