3d gravity in Bondi-Weyl gauge: charges, corners, and integrability
Résumé
We introduce a new gauge and solution space for three-dimensional gravity. As its name Bondi-Weyl suggests, it leads to non-trivial Weyl charges, and uses Bondi-like coordinates to allow for an arbitrary cosmological constant and therefore spacetimes which are asymptotically locally (A)dS or flat. We explain how integrability requires a choice of integrable slicing and also the introduction of a corner term. After discussing the holographic renormalization of the action and of the symplectic potential, we show that the charges are finite, symplectic and integrable, yet not conserved. We find four towers of charges forming an algebroid given by $ \mathfrak{vir}\oplus \mathfrak{vir}\oplus $ Heisenberg with three central extensions, where the base space is parametrized by the retarded time. These four charges generate diffeomorphisms of the boundary cylinder, Weyl rescalings of the boundary metric, and radial translations. We perform this study both in metric and triad variables, and use the triad to explain the covariant origin of the corner terms needed for renormalization and integrability.
Mots clés
Classical Theories of Gravity
Gauge Symmetry
Space-Time Symmetries
Conformal and W Symmetry
renormalization: holography
charge: Weyl
potential: symplectic
dimension: 3
integrability
gravitation
Heisenberg
cylinder
cosmological constant
covariance
diffeomorphism
conservation law
translation
rescaling
space-time