Observation of light-by-light scattering in ultraperipheral Pb+Pb collisions with the ATLAS detector

ATLAS Collaboration; Alan Watson

doi:10.1103/PhysRevLett.123.052001

Observation of light-by-light scattering in ultraperipheral Pb+Pb collisions with the ATLAS detector

ATLAS Collaboration, Alan Watson

Physics and Astronomy

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40 Citations (Scopus)

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Abstract

This Letter describes the observation of the light-by-light scattering process, γγ→γγ, in Pb+Pb collisions at √s_NN=5.02 TeV. The analysis is conducted using a data sample corresponding to an integrated luminosity of 1.73 nb^-1, collected in November 2018 by the ATLAS experiment at the LHC. Light-by-light scattering candidates are selected in events with two photons produced exclusively, each with transverse energy E_T^γ>3 GeV and pseudorapidity |η_γ|<2.4, diphoton invariant mass above 6 GeV, and small diphoton transverse momentum and acoplanarity. After applying all selection criteria, 59 candidate events are observed for a background expectation of 12±3 events. The observed excess of events over the expected background has a significance of 8.2 standard deviations. The measured fiducial cross section is 78±13(stat)±7(syst)±3(lumi) nb.

Original language	English
Article number	052001
Number of pages	21
Journal	Physical Review Letters
Volume	123
Issue number	5
Early online date	31 Jul 2019
DOIs	https://doi.org/10.1103/PhysRevLett.123.052001
Publication status	Published - 2 Aug 2019

Bibliographical note

28 pages in total, author list starting page 12, 3 figures, 0 tables, submitted to PRL. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2018-19

Keywords

hep-ex
nucl-ex

ASJC Scopus subject areas

General Physics and Astronomy

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10.1103/PhysRevLett.123.052001Licence: Creative Commons: Attribution (CC BY)

Aad_et_al_Observation_of_light_by_light_scattering_in_ultraperipheral__Pb+Pb_collisions_with_the_ATLAS_detector_Physical_Review_Letters_2019
Aad, G. et al, (2019) Observation of light-by-light scattering in ultraperipheral Pb+Pb collisions with the ATLAS detector, Physical Review Letters, vol. 123, article no. 052001, DOI: 10.1103/PhysRevLett.123.052001
Final published version, 432 KBLicence: Creative Commons: Attribution (CC BY)

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.123.052001Licence: Creative Commons: Attribution (CC BY)

Cite this

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title = "Observation of light-by-light scattering in ultraperipheral Pb+Pb collisions with the ATLAS detector",

abstract = "This Letter describes the observation of the light-by-light scattering process, γγ→γγ, in Pb+Pb collisions at √sNN=5.02 TeV. The analysis is conducted using a data sample corresponding to an integrated luminosity of 1.73 nb-1, collected in November 2018 by the ATLAS experiment at the LHC. Light-by-light scattering candidates are selected in events with two photons produced exclusively, each with transverse energy ETγ>3 GeV and pseudorapidity |ηγ|<2.4, diphoton invariant mass above 6 GeV, and small diphoton transverse momentum and acoplanarity. After applying all selection criteria, 59 candidate events are observed for a background expectation of 12±3 events. The observed excess of events over the expected background has a significance of 8.2 standard deviations. The measured fiducial cross section is 78±13(stat)±7(syst)±3(lumi) nb.",

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AB - This Letter describes the observation of the light-by-light scattering process, γγ→γγ, in Pb+Pb collisions at √sNN=5.02 TeV. The analysis is conducted using a data sample corresponding to an integrated luminosity of 1.73 nb-1, collected in November 2018 by the ATLAS experiment at the LHC. Light-by-light scattering candidates are selected in events with two photons produced exclusively, each with transverse energy ETγ>3 GeV and pseudorapidity |ηγ|<2.4, diphoton invariant mass above 6 GeV, and small diphoton transverse momentum and acoplanarity. After applying all selection criteria, 59 candidate events are observed for a background expectation of 12±3 events. The observed excess of events over the expected background has a significance of 8.2 standard deviations. The measured fiducial cross section is 78±13(stat)±7(syst)±3(lumi) nb.

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IS - 5

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Observation of light-by-light scattering in ultraperipheral Pb+Pb collisions with the ATLAS detector

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

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Cite this