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

Aaboud, M, Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Abeloos, B, Abidi, SH, AbouZeid, OS, Abraham, NL, Abramowicz, H
et al (show 2824 more authors) (2017) Evidence for light-by-light scattering in heavy-ion collisions with the ATLAS detector at the LHC. NATURE PHYSICS, 13 (9). 852-+.

Access the full-text of this item by clicking on the Open Access link.
[thumbnail of 1702.01625v1.pdf] Text
1702.01625v1.pdf - Published version

Download (1MB)


Light-by-light scattering ($\gamma\gamma\rightarrow\gamma\gamma$) 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 $\mu$b$^{-1}$ 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 $\gamma\gamma\rightarrow\gamma\gamma$ reaction. A total of 13 candidate events are observed with an expected background of 2.6$\pm$0.7 events. After background subtraction and analysis corrections, the fiducial cross section of the process $\textrm{Pb+Pb}\,(\gamma\gamma)\rightarrow \textrm{Pb}^{(\ast)}\textrm{+}\textrm{Pb}^{(\ast)}\,\gamma\gamma$, for photon transverse energy $E_{\mathrm{T}}>$3 GeV, photon absolute pseudorapidity $|\eta|<$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 $\pm$ 24 (stat.) $\pm$ 17 (syst.) nb, which is in agreement with Standard Model predictions.

Item Type: Article
Additional Information: 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/
Uncontrolled Keywords: hep-ex, hep-ex, nucl-ex
Depositing User: Symplectic Admin
Date Deposited: 22 Sep 2017 15:26
Last Modified: 19 Jan 2023 06:54
DOI: 10.1038/NPHYS4208
Open Access URL: https://arxiv.org/abs/1702.01625
Related URLs:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3009588