Orateur
Description
Symmetries impose powerful constraints on the structure of theories that are holographical dual to quantum gravity in the bulk spacetime. I will review recent progress on the structure of two-dimensional celestial CFTs conjectured to be dual to quantum gravity in four-dimensional asymptotically flat spacetimes where the set of symmetries underlying the universality of gravitational scattering in the infrared is particularly rich. Central to this the celestial operator product expansion (OPE), derived from the collinear limit of bulk scattering amplitudes, which for soft graviton operators determines the celestial symmetry algebra. While the discussion in the literature has mostly focused on tree-level soft physics, the long-range nature of gravitational interactions requires us to understand the implications of loop corrections. I will discuss our current understanding of those, present a new method for computing the celestial OPE at tree and loop level based on the consecutive double soft limit, and comment on the implications of these results for the structure of celestial CFT.