Evidence for light-by-light scattering in heavy-ion collisions with the ATLAS detector at the LHC

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Abstract

Light-by-light scattering (γγ → γγ) 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 ions. Using 480 μ1 of lead-lead collision data recorded at a centre-of-mass energy per nucleon pair of 5.02 TeV by the ATLAS detector, here we report evidence for light-by-light scattering. A total of 13 candidate events were 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 > 3GeV, photon absolute pseudorapidity |η| <2.4, diphoton invariant mass greater than 6GeV, diphoton transverse momentum lower than 2GeV and diphoton acoplanarity below 0.01, is measured to be 70 ± 24 (stat.) ±17 (syst.) nb, which is in agreement with the standard model predictions. © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.

Details

Authors
Organisations
External organisations
  • Mohamed Premier University
  • Aix-Marseille University
  • University of Oklahoma
  • University of Texas
  • Institute of Physics Azerbaijan National Academy of Sciences
  • University of Paris-Sud
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Subatomic Physics
Original languageEnglish
Pages (from-to)852-858
Number of pages7
JournalNature Physics
Volume13
Issue number9
Publication statusPublished - 2017
Publication categoryResearch
Peer-reviewedYes

Bibliographic note

Cited By :3 Export Date: 28 November 2017