Observation of Exclusive γγ Production in pp̅ Collisions at √s=1.96 TeV
Author(s)Gomez-Ceballos, Guillelmo; Goncharov, Maxim; Paus, Christoph M. E.
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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.
DepartmentMassachusetts Institute of Technology. Department of Physics; Massachusetts Institute of Technology. Laboratory for Nuclear Science
Physical Review Letters
American Physical Society
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
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