The Higgs-Gravity Connection

Abstract:
The geometrical formulation of gravity emerges naturally from the equivalence principle, hinting toward an intriguing connection with the concepts of mass and inertia. As already observed by Einstein, General Relativity can be expressed in a variety of ways, including not only the most common metric approach but also the Palatini, teleparallel, and Einstein-Cartan formulations. These realizations differ mainly in their choice of fundamental degrees of freedom, being otherwise mathematically equivalent as pure gravity is concerned. The degeneracy among different gravity incarnations breaks down, however, in the presence of non-minimal couplings to matter, as happens unavoidably when accounting for the Standard Model Higgs. This opens the possibility of testing the nature of gravity with cosmological observations. In this talk, I will provide an overview of this fascinating paradigm, describing its predictions, generalizations, open questions, and implications for the infamous hierarchy problem.