Observation of Exclusive γγ Production in pp̅ Collisions at √s=1.96 TeV
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Aaltonen-2012-Observation of Exclusive γγ Production.pdf
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Author(s)
Gomez-Ceballos, Guillelmo
Goncharov, Maxim
Paus, Christoph M. E.
Date Issued
February 2012
Journal
Physical Review Letters
Publisher
American Physical Society
Citation
Aaltonen et al. (CDF Collaboration) "Observation of Exclusive γγ Production in pp̅ Collisions at √s=1.96 TeV" Physical Review Letters 108, 081801 (2012). © 2012 American Physical Society
Version
Final published version
Abstract
We have observed exclusive γγ production in proton-antiproton collisions at √s=1.96 TeV, using data from 1.11±0.07 fb[superscript -1] integrated luminosity taken by the Run II Collider Detector at Fermilab. We selected events with two electromagnetic showers, each with transverse energy ET>2.5 GeV and pseudorapidity |η|<1.0, with no other particles detected in -7.4<η<+7.4. The two showers have similar ET and azimuthal angle separation ΔΦ ~π, 34 events have two charged particle tracks, consistent with the QED process pp̅ →p+e[superscript +]e[superscript -]p̅ by two-photon exchange, while 43 events have no charged tracks. The number of these events that are exclusive π[superscript 0]π[superscript 0] is consistent with zero and is <15 at 95% C.L. The cross section for pp̅ →p+γγ+p̅ with |η(γ)|<1.0 and ET(γ)>2.5 GeV is 2.48-0.35[superscript +0.40](stat)-0.51[superscript +0.40 (syst) pb.
MIT Department
Massachusetts Institute of Technology. Department of Physics
Massachusetts Institute of Technology. Laboratory for Nuclear Science
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DOI of Published Version
https://doi.org/10.1103/PhysRevLett.108.081801
