Séminaire par Matthieu Vilatte

Matthieu Vilatte (CPHT, École Polytechnique, Palaiseau) donnera le séminaire suivant dans la salle Mirzakhani :

Some features and applications of Carrollian physics

I will give an overview of Carrollian physics which is the physics naturally appearing at null infinity of asymptotically flat spacetimes. Starting by a review of the geometry of Carrollian spaces in a frame where the decoupling of time and space is apparent, I will show how to construct Carrollian momenta whose conservation equations follow from the invariance under Carrollian diffeomorphisms. The way to deal with Killing vectors and (non)-conserved charges will also be discussed with an accent on the example of the scalar field. Then, I will apply this theoretical framework within the flat fluid/gravity paradigm, first by discussing the gauge in which the expansion is performed. Finally, I will go through the conditions for the expansion to be resummable and present how one can, in the case of time independent Ricci-flat spacetimes, recover the gravitational multipoles from a pure Carrollian boundary viewpoint.