Charges in the Extended BMS Algebra: Definitions and Applications

TL;DR

This paper reviews recent advances in understanding symmetry charges in asymptotically flat spacetime, introducing dual supertranslations, a new local symmetry extending the BMS group, and proposing a novel description of Taub-NUT space.

Contribution

It introduces dual supertranslations as a new local symmetry extending the BMS group and offers a novel description of Taub-NUT space without closed time-like curves.

Findings

Reinterpretation of the boundary graviton reality constraint as gauge fixing of dual supertranslations

Proposal of a new Taub-NUT space description free of closed time-like curves

Progress in defining Lorentz and super-Lorentz charges that commute with supertranslations

Abstract

This is a review of selected topics from recent work on symmetry charges in asymptotically flat spacetime done by the author in collaboration with U. Kol and R. Javadinezhad. First we reinterpret the reality constraint on the boundary graviton as the gauge fixing of a new local symmetry, called dual supertranslations. This symmetry extends the BMS group and bears many similarities to the dual (magnetic) gauge symmetry of electrodynamics. We use this new gauge symmetry to propose a new description of the TAUB-NUT space that does not contain closed time-like curves. Next we summarize progress towards the definition of Lorentz and super-Lorentz charges that commute with supertranslations and with the soft graviton mode.