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Observation of proton-tagged, central (semi)exclusive production of high-mass lepton pairs in pp collisions at 13 TeV with the CMS-TOTEM precision proton spectrometer

par Sirunyan, A.M.;Beghin, Diego ;Bilin, Bugra ;Brun, Hugues ;Clerbaux, Barbara ;De Lentdecker, Gilles ;Delannoy, Hugo ;Dorney, Brian ;Fasanella, Giuseppe ;Favart, Laurent ;Goldouzian, Reza ;Grebenyuk, Anastasia ;Kalsi, Amandeep Kaur ;Lenzi, Thomas ;Luetic, Jelena ;Seva, Tomislav ;Starling, Elizabeth Rose ;Vander Velde, Catherine ;Vanlaer, Pascal ;Vannerom, David ;Yonamine, Ryo ;Fang, Wenxing ;Gao, Xuyang ; [et al.]
Référence The Journal of high energy physics, 2018, 7, 153
Publication Publié, 2018-07

Article révisé par les pairs

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Résumé :

The process pp → pℓ+ℓ−p(*), with ℓ+ℓ− a muon or an electron pair produced at midrapidity with mass larger than 110 GeV, has been observed for the first time at the LHC in pp collisions at s=13 TeV. One of the two scattered protons is measured in the CMS-TOTEM precision proton spectrometer (CT-PPS), which operated for the first time in 2016. The second proton either remains intact or is excited and then dissociates into a low-mass state p*, which is undetected. The measurement is based on an integrated luminosity of 9.4 fb−1 collected during standard, high-luminosity LHC operation. A total of 12 μ+μ− and 8 e+e− pairs with m(ℓ+ℓ−) > 110 GeV, and matching forward proton kinematics, are observed, with expected backgrounds of 1.49 ± 0.07 (stat) ± 0.53 (syst) and 2.36 ± 0.09 (stat) ± 0.47 (syst), respectively. This corresponds to an excess of more than five standard deviations over the expected background. The present result constitutes the first observation of proton-tagged γγ collisions at the electroweak scale. This measurement also demonstrates that CT-PPS performs according to the design specifications.