In:
Journal of High Energy Physics, Springer Science and Business Media LLC, Vol. 2018, No. 7 ( 2018-07)
Abstract:
The process pp → p ℓ + 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 $$ \sqrt{s}=13 $$ 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.
Type of Medium:
Online Resource
ISSN:
1029-8479
DOI:
10.1007/JHEP07(2018)153
Language:
English
Publisher:
Springer Science and Business Media LLC
Publication Date:
2018
detail.hit.zdb_id:
2027350-2
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