Asymptotically flat spacetimes with BMS ₃ symmetry

Abstract

We construct the phase space of 3-dimensional asymptotically flat spacetimes that forms the bulk metric representation of the BMS group consisting of both supertranslations and superrotations. The asymptotic symmetry group is a unique copy of the BMS group at both null infinities and spatial infinity. The BMS phase space obeys a notion of holographic causality and can be parametrized by boundary null fields. This automatically leads to the antipodal identification of bulk fields between past and future null infinity in the absence of a global conical defect. 1

The BMS4 algebra at spatial infinity

“…A similar analysis has been done in 3 dimensions by Compere and Fiorucci [18]. Their results are the 3 dimensional equivalent to the ones we report here.…”

Entanglement entropy in flat holography

“…Flat holography based on BMS 3 symmetry was proposed in [25,26] and supporting evidence can be found in [46][47][48]. The antipodal identification in three dimensions was discussed in [49,50]. See [51][52][53][54][55][56] for more discussions for this flat holography and related topics.…”

Geometric actions and flat space holography

“…11 Several subtleties and extensions of the work presented here deserve a comment. In this paper we have concerned ourselves exclusively with a single boundary, leaving aside the interesting and relevant question on how to connect I + and I − through the boundary theory/symmetries (see [116,117] for a 3D discussion on linking I + and I − a la [118]).…”