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

Barton, Adam Edward and Beattie, Michael and Bertram, Iain Alexander and Borissov, Guennadi and Bouhova-Thacker, Evelina Vassileva and Dearnaley, William and Fox, Harald and Grimm, Kathryn Ann Tschann and Henderson, Robert Charles William and Hughes, Gareth and Jones, Roger William Lewis and Kartvelishvili, Vakhtang and Long, Robin Eamonn and Love, Peter Allan and Muenstermann, Daniel Matthias Alfred and Parker, Adam Jackson and Skinner, Malcolm and Smizanska, Maria and Walder, James William and Wharton, Andy (2017) Evidence for light-by-light scattering in heavy-ion collisions with the ATLAS detector at the LHC. Nature physics, 13 (9). pp. 852-858. ISSN 1745-2473

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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 μb−1 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 > 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 the standard model predictions.

Item Type:
Journal Article
Journal or Publication Title:
Nature physics
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/3100
Subjects:
ID Code:
88916
Deposited By:
Deposited On:
24 Nov 2017 02:02
Refereed?:
Yes
Published?:
Published
Last Modified:
21 Sep 2020 02:30