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

, The ATLAS collaboration (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:
24 Sep 2021 07:46