TY - JOUR
T1 - 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
AU - The CMS collaboration
AU - Chatrchyan, S.
AU - Khachatryan, V.
AU - Sirunyan, A. M.
AU - Tumasyan, A.
AU - Adam, W.
AU - Bergauer, T.
AU - Dragicevic, M.
AU - Erö, J.
AU - Fabjan, C.
AU - Friedl, M.
AU - Frühwirth, R.
AU - Ghete, V. M.
AU - Hammer, J.
AU - Hörmann, N.
AU - Hrubec, J.
AU - Jeitler, M.
AU - Kiesenhofer, W.
AU - Knünz, V.
AU - Krammer, M.
AU - Liko, D.
AU - Mikulec, I.
AU - Pernicka, M.
AU - Rahbaran, B.
AU - Rohringer, C.
AU - Rohringer, H.
AU - Schöfbeck, R.
AU - Strauss, J.
AU - Taurok, A.
AU - Wagner, P.
AU - Waltenberger, W.
AU - Walzel, G.
AU - Widl, E.
AU - Wulz, C. E.
AU - Mossolov, V.
AU - Shumeiko, N.
AU - Suarez Gonzalez, J.
AU - Bansal, S.
AU - Cornelis, T.
AU - De Wolf, E. A.
AU - Janssen, X.
AU - Luyckx, S.
AU - Maes, T.
AU - Mucibello, L.
AU - Ochesanu, S.
AU - Roland, B.
AU - Rougny, R.
AU - Selvaggi, M.
AU - Staykova, Z.
AU - Van Haevermaet, H.
AU - Parida, B.
PY - 2012/1/1
Y1 - 2012/1/1
N2 - 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.
AB - 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.
KW - Hadron-Hadron Scattering
UR - http://www.scopus.com/inward/record.url?scp=84870369180&partnerID=8YFLogxK
U2 - 10.1007/JHEP11(2012)080
DO - 10.1007/JHEP11(2012)080
M3 - Article
AN - SCOPUS:84870369180
SN - 1126-6708
VL - 2012
JO - Journal of High Energy Physics
JF - Journal of High Energy Physics
IS - 11
M1 - 80
ER -