Search for exclusive or semi-exclusive γ γ production and observation of exclusive and semi-exclusive e+e- production in pp collisions at √ s = 7 TeV

The CMS Collaboration

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Abstract

A search for exclusive or semi-exclusive production, pp → p(*) +γ γ+p(*) (where p* stands for a diffractively- dissociated proton), and the observation of exclusive and semi-exclusive e +e- production, pp → p(*) + e+e - + p(*), in proton-proton collisions at √s = 7TeV, are presented. The analysis is based on a data sample corresponding to an integrated luminosity of 36 pb-1 recorded by the CMS experiment at the LHC at low instantaneous luminosities. Candidate γ γor e+e - events are selected by requiring the presence of two photons or a positron and an electron, each with transverse energy ET > 5.5 GeV and pseudorapidity |η| < 2.5, and no other particles in the region |η| < 5.2. No exclusive or semi-exclusive diphoton candidates are found in the data. An upper limit on the cross section for the reaction pp → p(*) +γ γ+ p(*), within the above kinematic selections, is set at 1.18 pb at 95% confidence level. Seventeen exclusive or semi-exclusive dielectron candidates are observed, with an estimated background of 0.85 ± 0.28 (stat.) events, in agreement with the QED-based prediction of 16.3 ± 1.3 (syst.) events.

Original languageEnglish (US)
Article number80
JournalJournal of High Energy Physics
Volume2012
Issue number11
DOIs
StatePublished - 2012

Keywords

  • Hadron-Hadron Scattering

ASJC Scopus subject areas

  • Nuclear and High Energy Physics

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