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

ATLAS Collaboration

Research output: Contribution to journalArticlepeer-review

150 Citations (Scopus)
5 Downloads (Pure)

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.

Original languageEnglish
Article number052001
Pages (from-to)052001-1-052001-21
Number of pages21
JournalPhysical Review Letters
Volume123
Issue number5
DOIs
Publication statusPublished - 2 Aug 2019
Externally publishedYes

Bibliographical note

Copyright the Author(s) 2019. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

Cite this