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
Author(s)
CMS Collaboration; TOTEM Collaboration; Abercrombie, Daniel Robert; Allen, Brandon Leigh; Azzolini, Virginia; Barbieri, Richard Alexander; Baty, Austin Alan; Bauer, Gerry P; Bi, Ran; Brandt, Stephanie Akemi; Busza, Wit; Cali, Ivan Amos; D'Alfonso, Mariarosaria; Demiragli, Zeynep; Gomez-Ceballos, Guillelmo; Goncharov, Maxim; Harris, Philip Coleman; Hsu, Dylan George; Hu, Miao; Iiyama, Yutaro; Innocenti, Gian Michele; Klute, Markus; Kovalskyi, Dmytro; Lee, Yen-Jie; Levin, Amy Elizabeth; Luckey Jr, P David; Maier, Benedikt; Marini, Andrea Carlo; McGinn, Christopher Francis; Mironov, Camelia Maria; Narayanan, Siddharth Madhavan; Niu, Xinmei; Paus, Christoph M. E.; Roland, Christof E; Roland, Gunther M; Stephans, George S. F.; Sumorok, Konstanty C; Tatar, Kaya; Velicanu, Dragos Alexandru; Wang, Jing; Wang, Ta-Wei; Wyslouch, Boleslaw; Zhaozhong, S.; ... Show more Show less
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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. Keywords: Forward physics; Hadron-Hadron scattering (experiments); Photon production; proton-proton scattering
Date issued
2018-07Department
Massachusetts Institute of Technology. Department of Physics; Massachusetts Institute of Technology. Laboratory for Nuclear ScienceJournal
Journal of High Energy Physics
Publisher
Springer Berlin Heidelberg
Citation
Sirunyan, A. M. et al. “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.” Journal of High Energy Physics 2018, 7 (July 2018): 153 © 2018 The Author(s)
Version: Final published version
ISSN
1029-8479