## Lorentz violations in gravity

IFPU & online

July 10 – 14, 2023

Lorentz symmetry allows reconciling Maxwell’s electromagnetism with the principle of relativity, which states that the result of experiments should be the same for all inertial observers. This reconciliation was the basis of Einstein’s Special Relativity. Einstein later formulated GR as a Lorentz symmetric completion of Newtonian gravity. Today, much of theoretical physics is built on Lorentz symmetry. In particular, it is a cornerstone of the standard model of particle physics. Given how embedded this symmetry is in our understanding of Nature, any hint of its violation would shake physics at its core. Given its importance, it is quite surprising that bounds on Lorentz symmetry violations in gravity are rather weak, compared to the exquisite tests of this symmetry that have been carried out in the matter sector (with high-energy cosmic rays). This knowledge gap is even more striking in the light of recent developments in quantum gravity, whereby giving up Lorentz symmetry (and in particular boost symmetry) allows for constructing gravitational theories that are power counting and perturbatively renormalizable. This program investigates Lorentz violations in gravitational physics from both a theoretical and phenomenological/astrophysical point of view.

Reference webpage: https://grams-815673.wixsite.com/lorentzviolation.

Scientific organizers:

- Enrico Barausse (SISSA)
- Stefano Liberati (SISSA)
- Mario Herrero-Valea (Barcelona)