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Article
Report number arXiv:1702.01625 ; CERN-EP-2016-316
Title Evidence for light-by-light scattering in heavy-ion collisions with the ATLAS detector at the LHC
Related titleEvidence for light-by-light scattering in heavy-ion collisions with the ATLAS detector at the LHC
Author(s) ATLAS Collaboration  Afficher les 2847 auteurs
Publication 2017-08-14
Imprint 06 Feb 2017
Number of pages 31
Note 34 pages in total, author list starting page 18, 6 figures, 2 tables. published version. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2016-05/
In: Nature Phys. 13 (2017) 852-858
DOI 10.1038/nphys4208
Subject category Particle Physics - Experiment ; nucl-ex ; Nuclear Physics - Experiment ; hep-ex
Accelerator/Facility, Experiment CERN LHC ; ATLAS
Free keywords electroweak interaction ; photon production ; experimental results
Abstract Light-by-light scattering (γγγγ) is a quantum-mechanical process that is forbidden in the classical theory of electrodynamics. This reaction is accessible at the Large Hadron Collider thanks to the large electromagnetic field strengths generated by ultra-relativistic colliding lead (Pb) ions. Using 480 μb1 of Pb+Pb collision data recorded at a centre-of-mass energy per nucleon pair of 5.02 TeV by the ATLAS detector, the ATLAS Collaboration reports evidence for the γγγγ reaction. A total of 13 candidate events are observed with an expected background of 2.6±0.7 events. After background subtraction and analysis corrections, the fiducial cross section of the process Pb+Pb(γγ)Pb()+Pb()γγ, for photon transverse energy ET>3 GeV, photon absolute pseudorapidity |η|<2.4, diphoton invariant mass greater than 6 GeV, diphoton transverse momentum lower than 2 GeV and diphoton acoplanarity below 0.01, is measured to be 70±24 (stat.) ±17 (syst.) nb, which is in agreement with Standard Model predictions.
Copyright/License Preprint: © 2016-2025 CERN (License: CC-BY-4.0)
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