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Infrared Consistency and the Weak Gravity Conjecture

Cheung, Clifford and Remmen, Grant N. (2014) Infrared Consistency and the Weak Gravity Conjecture. Journal of High Energy Physics, 2014 (12). Art. No. 087. ISSN 1126-6708. doi:10.1007/JHEP12(2014)087.

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The weak gravity conjecture (WGC) asserts that an Abelian gauge theory coupled to gravity is inconsistent unless it contains a particle of charge q and mass m such that q≥m/m_(Pl). This criterion is obeyed by all known ultraviolet completions and is needed to evade pathologies from stable black hole remnants. In this paper, we explore the WGC from the perspective of low-energy effective field theory. Below the charged particle threshold, the effective action describes a photon and graviton interacting via higher-dimension operators. We derive infrared consistency conditions on the parameters of the effective action using i ) analyticity of light-by-light scattering, ii ) unitarity of the dynamics of an arbitrary ultraviolet completion, and iii ) absence of superluminality and causality violation in certain non-trivial backgrounds. For convenience, we begin our analysis in three spacetime dimensions, where gravity is non-dynamical but has a physical effect on photon-photon interactions. We then consider four dimensions, where propagating gravity substantially complicates all of our arguments, but bounds can still be derived. Operators in the effective action arise from two types of diagrams: those that involve electromagnetic interactions (parameterized by a charge-to-mass ratio q/m) and those that do not (parameterized by a coefficient γ). Infrared consistency implies that q/m is bounded from below for small γ.

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Remmen, Grant N.0000-0001-6569-8866
Additional Information:© 2014 The Author(s). 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. Article funded by SCOAP3. Received: August 30, 2014; Accepted: November 21, 2014; Published: December 11, 2014. We thank Allan Adams, Nima Arkani-Hamed, Brando Bellazzini, Sean Carroll, Stanley Deser, Tim Hollowood, Stefan Leichenauer, Alberto Nicolis, Rafael Porto, and Ira Rothstein for useful discussions and comments. C.C. is supported by a Sloan Research Fellowship and a DOE Early Career Award under Grant No. DE-SC0010255. G.N.R. is supported by a Hertz Graduate Fellowship and a NSF Graduate Research Fellowship under Grant No. DGE-1144469.
Group:Walter Burke Institute for Theoretical Physics, Caltech Theory
Funding AgencyGrant Number
Alfred P. Sloan FoundationUNSPECIFIED
Department of Energy (DOE)DE-SC0010255
Fannie and John Hertz FoundationUNSPECIFIED
NSF Graduate Research FellowshipDGE-1144469
Subject Keywords:Scattering Amplitudes, Electromagnetic Processes and Properties, Gauge Symmetry, Classical Theories of Gravity
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Issue or Number:12
Record Number:CaltechAUTHORS:20140813-093110999
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Official Citation:Cheung, C. & Remmen, G.N. J. High Energ. Phys. (2014) 2014: 87. doi:10.1007/JHEP12(2014)087
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:48493
Deposited By: Joy Painter
Deposited On:13 Aug 2014 19:48
Last Modified:10 Nov 2021 18:32

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