Measurement of event-shape observables in Z → ℓ+ℓ− events in pp collisions at √ s = 7 TeV with the ATLAS detector at the LHC

G Aad, B. Abbott, J Abdallah, O Abdinov, B Abeloos, R Aben, Torsten Åkesson, Simona Bocchetta, LENE BRYNGEMARK, Caterina Doglioni, Anders Floderus, Anthony Hawkins, Vincent Hedberg, Jenny Ivarsson, Göran Jarlskog, Else Lytken, Ulf Mjörnmark, Oxana Smirnova, Oleksandr Viazlo, ATLAS Collaboration

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Event-shape observables measured using charged particles in inclusive Z-boson events are presented, using the electron and muon decay modes of the Z bosons. The measurements are based on an integrated luminosity of 1.1 fb−1 of proton-proton collisions recorded by the ATLAS detector at theLHCat a centre-of-mass energy √ s = 7TeV.Chargedparticle distributions, excluding the lepton-antilepton pair from the Z-boson decay, are measured in different ranges of transverse momentum of the Z boson. Distributions include multiplicity, scalar sum of transverse momenta, beam thrust, transverse thrust, spherocity, and F-parameter, which are in particular sensitive to properties of the underlying event at small values of the Z-boson transverse momentum. The measured observables are compared with predictions from Pythia 8, Sherpa, and Herwig7. Typically, all three Monte Carlo generators provide predictions that are in better agreement with the data at high Z-boson transverse momenta than at low Z-boson transverse momenta, and for the observables that are less sensitive to the number of charged particles in the event. © CERN for the benefit of the ATLAS collaboration 2016.
Original languageEnglish
Article number375
Number of pages2
JournalEuropean Physical Journal C
Issue number7
Publication statusPublished - 2016

Bibliographical note

Export Date: 25 July 2017

Subject classification (UKÄ)

  • Subatomic Physics


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