Finite BMS transformations
Glenn Barnich, Cédric Troessaert
TL;DR
The paper develops a systematic framework for finite BMS and Weyl transformations acting on gravitational data at Scri in three and four dimensions, allowing for an arbitrary boundary conformal factor. It combines adapted Cartan and Newman-Penrose formalisms to derive how asymptotic solution spaces transform under the full symmetry groups, including the Schwarzian-type structures in AdS3 and the extended BMS4 group with complex rescalings in NU and NP formalisms. Key results include explicit transformation laws for boundary data, mass and angular momentum aspects, and Weyl-invariant contents of the solution space, providing a basis for Ward identities and memory-effect analyses in both AdS and flat settings. The work sets the stage for deeper physical applications of asymptotic symmetries, such as constraints on scattering and memory phenomena, across different spacetime dimensions and topologies.
Abstract
The action of finite BMS and Weyl transformations on the gravitational data at null infinity is worked out in three and four dimensions in the case of an arbitrary conformal factor for the boundary metric induced on Scri.
