CENTRA Seminar - Status of Hořava gravity: theory, black holes and cosmology - 31 maio 2017

I will discuss the status of Hořava gravity which has been proposed as an ultraviolet completion to General Relativity. Adding to the gravitational action higher-order spatial derivatives without adding higher-order time derivatives leads to a modification of the graviton propagator, which renders the theory power-counting renormalizable at the expense of violating Lorentz symmetry at all scales. Perhaps surprisingly, the theory appears to be phenomenologically viable in its more general form. I will first talk about the foundations of the theory and its various versions proposed so far. Then, I will discuss the consequences of Lorentz invariance breaking for the causal properties of black hole spacetimes. Finally, I will present the cosmology of the low-energy limit of the theory and place tight constraints on its parameters using several cosmological data sets.