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4D scattering amplitudes and asymptotic symmetries from 2D CFT

Cheung, Clifford and de la Fuente, Anton and Sundrum, Raman (2017) 4D scattering amplitudes and asymptotic symmetries from 2D CFT. Journal of High Energy Physics, 2017 (1). Art. No. 112. ISSN 1029-8479. doi:10.1007/JHEP01(2017)112.

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We reformulate the scattering amplitudes of 4D flat space gauge theory and gravity in the language of a 2D CFT on the celestial sphere. The resulting CFT structure exhibits an OPE constructed from 4D collinear singularities, as well as infinite-dimensional Kac-Moody and Virasoro algebras encoding the asymptotic symmetries of 4D flat space. We derive these results by recasting 4D dynamics in terms of a convenient foliation of flat space into 3D Euclidean AdS and Lorentzian dS geometries. Tree-level scattering amplitudes take the form of Witten diagrams for a continuum of (A)dS modes, which are in turn equivalent to CFT correlators via the (A)dS/CFT dictionary. The Ward identities for the 2D conserved currents are dual to 4D soft theorems, while the bulk-boundary propagators of massless (A)dS modes are superpositions of the leading and subleading Weinberg soft factors of gauge theory and gravity. In general, the massless (A)dS modes are 3D Chern-Simons gauge fields describing the soft, single helicity sectors of 4D gauge theory and gravity. Consistent with the topological nature of Chern-Simons theory, Aharonov-Bohm effects record the “tracks” of hard particles in the soft radiation, leading to a simple characterization of gauge and gravitational memories. Soft particle exchanges between hard processes define the Kac-Moody level and Virasoro central charge, which are thereby related to the 4D gauge coupling and gravitational strength in units of an infrared cutoff. Finally, we discuss a toy model for black hole horizons via a restriction to the Rindler region.

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Additional Information:© 2017 The Author(s). Open Access. This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited. C.C. is supported by a Sloan Research Fellowship and a DOE Early Career Award under Grant No. DE-SC0010255. A.D. and R.S. are supported in part by the NSF under Grant No. PHY-1315155 and by the Maryland Center for Fundamental Physics. R.S. would also like to thank the Gordon and Betty Moore Foundation for the award of a Moore Distinguished Scholar Fellowship to visit Caltech, as well as the hospitality of the Walter Burke Institute for Theoretical Physics, where a substantial part of this work was completed. The authors are grateful to Nima Arkani-Hamed, Ricardo Caldeira Costa, Liam Fitzpatrick, Ted Jacobson, Dan Kapec, Jared Kaplan, Juan Maldacena, Ira Rothstein, and Anthony Speranza for useful discussions and comments.
Group:Walter Burke Institute for Theoretical Physics
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Alfred P. Sloan FoundationUNSPECIFIED
Department of Energy (DOE)DE-SC0010255
Maryland Center for Fundamental PhysicsUNSPECIFIED
Gordon and Betty Moore FoundationUNSPECIFIED
Walter Burke Institute for Theoretical Physics, CaltechUNSPECIFIED
Subject Keywords:AdS-CFT Correspondence, Conformal Field Theory, Scattering Amplitudes
Issue or Number:1
Record Number:CaltechAUTHORS:20170419-075551109
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Official Citation:Cheung, C., de la Fuente, A. & Sundrum, R. J. High Energ. Phys. (2017) 2017: 112. doi:10.1007/JHEP01(2017)112
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:76653
Deposited By: Ruth Sustaita
Deposited On:19 Apr 2017 16:11
Last Modified:15 Nov 2021 17:01

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