A New Gauge for Asymptotically Flat Spacetime

2021/12/21 by Krishnan, Chethan, Pereira, Jude
#FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #High Energy Physics - Theory (hep-th)

paper · doi:10.48550/arxiv.2112.11440

Abstract

We present a new gauge for asymptotically flat spacetime that can treat future and past null infinities (\mathscrI⁺ or \mathscrI^-) democratically. Our gauge is complementary to Bondi and Ashtekar-Hansen gauges, and is adapted to the S-matrix being the natural observable. One new feature is that the holographic directions are null. We present a set of consistent fall-offs in terms of null coordinates at \mathscrI⁺ and \mathscrI^-, with finite BMS^± charges. The diagonal BMS⁰ symmetry of the gravitational S-matrix emerges upon demanding \em asymptotic CPT invariance. Trivial diffeomorphisms, (absence of) log fall-offs, possible enhancements of BMS algebra, and the possibility of holographic renormalization of data at \mathscrI⁺_- and \mathscrI^-₊, play interesting roles. Gory details of the various new technical features that emerge, are elaborated in a companion paper to this letter.

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