Exclusive dielectron production in ultraperipheral Pb+Pb collisions at √sNN = 5.02 TeV with ATLAS

ATLAS Collaboration, Paul Newman

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Exclusive production of dielectron pairs, γγ→e+e, is studied using Lint=1.72nb−1 of data from ultraperipheral collisions of lead nuclei at √sNN = 5.02 TeV recorded by the ATLAS detector at the LHC. The process of interest proceeds via photon-photon interaction in the strong electromagnetic fields of relativistic lead nuclei. Dielectron production is measured in the fiducial region defined by following requirements: electron transverse momentum, peT>2.5 GeV, absolute electron pseudorapidity, |ηe|<2.5, invariant mass of the dielectron system, mee>5 GeV, and transverse momentum of the dielecton pair, peeT<2 GeV. Differential cross-sections are measured as a function of mee, average peT, absolute rapidity of the dielectron system, |yee|, and scattering angle in the dielectron rest frame, |cosθ| in the inclusive sample, and also under the requirement of no activity in the forward direction. The total integrated fiducial cross-section is measured to be 215±1(stat.)+23−20(syst.)±4(lumi.)μb. Within experimental uncertainties the measured integrated cross-section is in good agreement with the QED predictions from the Monte Carlo programs Starlight and SuperChic, confirming the broad features of the initial photon fluxes. The differential cross-sections show systematic differences with these predictions which are more pronounced at high |yee| and |cosθ| values.
Original languageEnglish
Article number182
Number of pages42
JournalJournal of High Energy Physics
Publication statusPublished - 27 Jun 2023

Bibliographical note

21 pages in total, 7 figures, 0 tables, submitted to JHEP. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2021-16


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