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Measurement of exclusive γγ → +− production in proton–proton collisions at √s = 7 TeV with the ATLAS detector

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<mark>Journal publication date</mark>7/10/2015
<mark>Journal</mark>Physics Letters B
Number of pages20
Pages (from-to)242-261
Early online date31/07/15
<mark>Original language</mark>English


This Letter reports a measurement of the exclusive γγ → +− ( = e, μ) cross-section in proton–proton collisions at a centre-of-mass energy of 7 TeV by the ATLAS experiment at the LHC, based on an integrated luminosity of 4.6 fb−1. For the electron or muon pairs satisfying exclusive selection criteria, a fit to the dilepton acoplanarity distribution is used to extract the fiducial cross-sections. The cross-section in the electron channel is determined to be σexcl. γγ→e+e− = 0.428 ± 0.035 (stat.) ± 0.018 (syst.) pb for a phase–space region with invariant mass of the electron pairs greater than 24 GeV, in which both electrons have transverse momentum pT > 12 GeV and pseudorapidity |η| < 2.4. For muon pairs with invariant mass greater than 20 GeV, muon transverse momentum pT > 10 GeV and pseudorapidity |η| < 2.4, the cross-section is determined to be σexcl. γγ→μ+μ− = 0.628 ± 0.032 (stat.) ± 0.021 (syst.) pb. When proton absorptive effects due to the finite size of the proton are taken into account in the theory calculation, the measured cross-sections are found to be consistent with the theory prediction.