From UV completeness to black hole physics: lessons from Hořava Gravity and Asymptotic Safety

Abstract

In the search for a consistent and renormalizable quantum theory of gravity, a conservative possibility is that gravity admits a field-theoretic description valid up to arbitrarily high energies. This amounts to going beyond the perturbative non-renormalizability of general relativity and it can be achieved following different strategies. One is to abandon Lorentz invariance as a fundamental symmetry to gain power-counting renormalizability, as in Hořava Gravity. In Asymptotically Safe Gravity, ultraviolet completeness instead arises from a non-perturbative renormalization group fixed point, preserving spacetime symmetries. In both cases, the peculiar UV structure of the theory reflects in its low-energy description, with a particular imprint on black hole physics. In this talk, I will explore these two scenarios as UV description of gravity. I will focus both on their high-energy description, reviewing some recent developments, and on the possible low-energy physics stemming from each assumption.