Search for exclusive or semi-exclusive photon pair production and observation of exclusive and semi-exclusive electron pair production in pp collisions at s√=7 TeV
(2012) Journal of High Energy Physics — Vol. 1211, p. 2012 (080) (2012)
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- Abstract
- A search for exclusive or semi-exclusive γγ production, pp → p(*) + γγ + 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√=7 TeV, 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 γγ or e+e− events are selected by requiring the presence of two photons or a positron and an electron, each with transverse energy E T > 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(*) + γγ + 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.
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CMS Collaboration, Quertenmont, L., Basegmez, S., Bruno, G., Castello, R., Caudron, A., Ceard, L., Delaere, C., Du Pree, T., Favart, D., Forthomme, L., Giammanco, A., Hollar, J., Lemaitre, V., Liao, J., Militaru, O., Nuttens, C., Pagano, D., Perrini, L., et al. (2012). Search for exclusive or semi-exclusive photon pair production and observation of exclusive and semi-exclusive electron pair production in pp collisions at s√=7 TeV. Journal of High Energy Physics, 1211, 2012 (080). https://doi.org/10.1007/JHEP11(2012)080 (Original work published 2012)