Jet and underlying event properties as a function of charged-particle multiplicity in proton–proton collisions at √s = 7 TeV
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10052_2013_Article_2674.pdf
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Author(s)
Chatrchyan, S.
Khachatryan, V.
Sirunyan, A. M
Tumasyan, A.
Adam, W.
Bergauer, T.
Dragicevic, M.
Erö, J.
Fabjan, C.
Friedl, M.
Date Issued
December 2013
Journal
European Physical Journal C: Particles and Fields
Publisher
Springer Berlin Heidelberg
Citation
Chatrchyan, S. et al. "Jet and underlying event properties as a function of charged-particle multiplicity in proton–proton collisions at √s = 7 TeV." The European Physical Journal C 73, 12 (December 2013): 2674 © 2013 CERN for the benefit of the CMS collaboration
Version
Final published version
Abstract
Abstract
Characteristics of multi-particle production in proton-proton collisions at √s = 7 TeV are studied as a function of the charged-particle multiplicity, N ch. The produced particles are separated into two classes: those belonging to jets and those belonging to the underlying event. Charged particles are measured with pseudorapidity |η|<2.4 and transverse momentum pT>0.25 GeV/c. Jets are reconstructed from charged-particles only and required to have pT>5 GeV/c. The distributions of jet pT, average pT of charged particles belonging to the underlying event or to jets, jet rates, and jet shapes are presented as functions of Nch and compared to the predictions of the pythia and herwig event generators. Predictions without multi-parton interactions fail completely to describe the Nch-dependence observed in the data. For increasing Nch, pythia systematically predicts higher jet rates and harder pT spectra than seen in the data, whereas herwig shows the opposite trends. At the highest multiplicity, the data–model agreement is worse for most observables, indicating the need for further tuning and/or new model ingredients.
Characteristics of multi-particle production in proton-proton collisions at √s = 7 TeV are studied as a function of the charged-particle multiplicity, N ch. The produced particles are separated into two classes: those belonging to jets and those belonging to the underlying event. Charged particles are measured with pseudorapidity |η|<2.4 and transverse momentum pT>0.25 GeV/c. Jets are reconstructed from charged-particles only and required to have pT>5 GeV/c. The distributions of jet pT, average pT of charged particles belonging to the underlying event or to jets, jet rates, and jet shapes are presented as functions of Nch and compared to the predictions of the pythia and herwig event generators. Predictions without multi-parton interactions fail completely to describe the Nch-dependence observed in the data. For increasing Nch, pythia systematically predicts higher jet rates and harder pT spectra than seen in the data, whereas herwig shows the opposite trends. At the highest multiplicity, the data–model agreement is worse for most observables, indicating the need for further tuning and/or new model ingredients.
MIT Department
Massachusetts Institute of Technology. Department of Physics
Massachusetts Institute of Technology. Laboratory for Nuclear Science
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DOI of Published Version
http://dx.doi.org/10.1140/epjc/s10052-013-2674-5
