Séminaires des Cordes

Séminaires des Cordes
le mercredi 23 mars 2022
Salle de conférence Louis Michel, CPHT, Ecole Polytechnique

11h - 11h45
Luca Ciambelli
Universal symmetries of gravity
Abstract: I will derive the universal group of symmetries stemming from diffeomorphisms on a codimension-2 surface S at finite distance. I will then compute Noether charges in Einstein gravity and prove that, treating the embedding fields carefully, their algebra is a faithful representation of the aforementioned group of symmetries. This is then shown to be canonically realized on a suitably enlarged covariant field space, where one treats the embedding fields as part of the field space. This solves an old question in gravity, which is to find a field space where all gravitational charges are canonical, i.e. integrable, and thus represented through Poisson brackets.

12h - 12h45
Romain Ruzziconi
A Carrollian Perspective on Celestial Holography
Abstract: I will present a holographic description of gravity in 4d asymptotically flat spacetime in terms of a 3d sourced conformal Carrollian field theory. The external sources encode the leaks of gravitational radiation at null infinity. The Ward identities of this theory are shown to reproduce those of the 2d celestial CFT after relating Carrollian to celestial operators. This suggests a new set of interplays between gravity in asymptotically flat spacetime, sourced conformal Carrollian field theory and celestial CFT.