Celestial amplitudes and conformal soft theorems

Scattering amplitudes in d  +  2 dimensions can be expressed in terms of a conformal basis, for which the S-matrix behaves as a CFT correlation function on the celestial d-sphere. We explain how compact expressions for the full tree-level S-matrix of gauge theory, gravity and other QFTs extend to th...

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Main Authors: Adamo, T, Mason, L, Sharma, A
Format: Journal article
Language:English
Published: IOP Publishing 2019
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author Adamo, T
Mason, L
Sharma, A
author_facet Adamo, T
Mason, L
Sharma, A
author_sort Adamo, T
collection OXFORD
description Scattering amplitudes in d  +  2 dimensions can be expressed in terms of a conformal basis, for which the S-matrix behaves as a CFT correlation function on the celestial d-sphere. We explain how compact expressions for the full tree-level S-matrix of gauge theory, gravity and other QFTs extend to this conformal basis, and are easily derived from ambitwistor strings. Using these formulae and their worldsheet origins, we prove various tree-level 'conformal soft theorems' in gauge theory and gravity in any dimension; these arise from limits where the scaling dimension of an external state in the scattering process takes special values. These conformally soft limits are obscure from standard methods, but they are easily derived with ambitwistor strings. Additionally, we make an identification between the residues of conformally soft vertex operator insertions in ambitwistor strings and charges generating asymptotic symmetries.
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spelling oxford-uuid:2a084838-6e7d-4cac-aba3-3fa660340d6d2022-03-26T12:22:36ZCelestial amplitudes and conformal soft theoremsJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:2a084838-6e7d-4cac-aba3-3fa660340d6dEnglishSymplectic Elements at OxfordIOP Publishing2019Adamo, TMason, LSharma, AScattering amplitudes in d  +  2 dimensions can be expressed in terms of a conformal basis, for which the S-matrix behaves as a CFT correlation function on the celestial d-sphere. We explain how compact expressions for the full tree-level S-matrix of gauge theory, gravity and other QFTs extend to this conformal basis, and are easily derived from ambitwistor strings. Using these formulae and their worldsheet origins, we prove various tree-level 'conformal soft theorems' in gauge theory and gravity in any dimension; these arise from limits where the scaling dimension of an external state in the scattering process takes special values. These conformally soft limits are obscure from standard methods, but they are easily derived with ambitwistor strings. Additionally, we make an identification between the residues of conformally soft vertex operator insertions in ambitwistor strings and charges generating asymptotic symmetries.
spellingShingle Adamo, T
Mason, L
Sharma, A
Celestial amplitudes and conformal soft theorems
title Celestial amplitudes and conformal soft theorems
title_full Celestial amplitudes and conformal soft theorems
title_fullStr Celestial amplitudes and conformal soft theorems
title_full_unstemmed Celestial amplitudes and conformal soft theorems
title_short Celestial amplitudes and conformal soft theorems
title_sort celestial amplitudes and conformal soft theorems
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AT masonl celestialamplitudesandconformalsofttheorems
AT sharmaa celestialamplitudesandconformalsofttheorems