Definitions of angular momentum and super angular momentum in asymptotically flat spacetimes: Properties and applications to compact-binary mergers

Abstract Two dimensional field theories with Bondi-Metzner-Sachs symmetry have been proposed as duals to asymptotically flat spacetimes in three dimensions. These field theories are naturally defined on null surfaces and hence are conformal cousins of Carrollian theories, where the speed of light goes to zero. In this paper, we initiate an investigation of anomalies in these field theories. Specifically, we focus on the BMS equivalent of Weyl invariance and its breakdown in these field theories and derive an expression for Weyl anomaly. Considering the transformation of partition functions under this symmetry, we derive a Carrollian Liouville action different from ones obtained in the literature earlier.

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Soft photon theorem in the small negative cosmological constant limit

Journal of High Energy Physics ◽

10.1007/jhep08(2021)105 ◽

2021 ◽

Vol 2021 (8) ◽

Author(s):

Nabamita Banerjee ◽

Karan Fernandes ◽

Arpita Mitra

Keyword(s):

Cosmological Constant ◽

Tree Level ◽

Leading Order ◽

Asymptotically Flat ◽

Soft Factor ◽

Flat Spacetime ◽

Electromagnetic Interactions ◽

Flat Spacetimes ◽

Perturbative Corrections ◽

Soft Factors

Abstract We study the effect of electromagnetic interactions on the classical soft theorems on an asymptotically AdS background in 4 spacetime dimensions, in the limit of a small cosmological constant or equivalently a large AdS radius l. This identifies 1/l2 perturbative corrections to the known asymptotically flat spacetime leading and subleading soft factors. Our analysis is only valid to leading order in 1/l2. The leading soft factor can be expected to be universal and holds beyond tree level. This allows us to derive a 1/l2 corrected Ward identity, following the known equivalence between large gauge Ward identities and soft theorems in asymptotically flat spacetimes.

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Observations of Hawking radiation: the Page curve and baby universes

Journal of High Energy Physics ◽

10.1007/jhep04(2021)272 ◽

2021 ◽

Vol 2021 (4) ◽

Author(s):

Donald Marolf ◽

Henry Maxfield

Keyword(s):

Black Holes ◽

Quantum Systems ◽

Late Time ◽

Asymptotically Flat ◽

Black Hole Information ◽

Flat Spacetimes ◽

The Cost ◽

Baby Universes ◽

Time Extrapolation ◽

Asymptotic Observers

AbstractWe reformulate recent insights into black hole information in a manner emphasizing operationally-defined notions of entropy, Lorentz-signature descriptions, and asymptotically flat spacetimes. With the help of replica wormholes, we find that experiments of asymptotic observers are consistent with black holes as unitary quantum systems, with density of states given by the Bekenstein-Hawking formula. However, this comes at the cost of superselection sectors associated with the state of baby universes. Spacetimes studied by Polchinski and Strominger in 1994 provide a simple illustration of the associated concepts and techniques, and we argue them to be a natural late-time extrapolation of replica wormholes. The work aims to be self-contained and, in particular, to be accessible to readers who have not yet mastered earlier formulations of the ideas above.

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