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Torsten ÅKESSON

Torsten Åkesson

Professor

Torsten ÅKESSON

Measurements of Zγ and Zγγ production in pp collisions at s =8 TeV with the ATLAS detector

Author

  • G Aad
  • B. Abbott
  • J Abdallah
  • 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

Summary, in English

The production of Z bosons with one or two isolated high-energy photons is studied using pp collisions at s=8 TeV. The analyses use a data sample with an integrated luminosity of 20.3 fb-1 collected by the ATLAS detector during the 2012 LHC data taking. The Zγ and Zγγ production cross sections are measured with leptonic (e+e-, μ+μ-, νν) decays of the Z boson, in extended fiducial regions defined in terms of the lepton and photon acceptance. They are then compared to cross-section predictions from the Standard Model, where the sources of the photons are radiation off initial-state quarks and radiative Z-boson decay to charged leptons, and from fragmentation of final-state quarks and gluons into photons. The yields of events with photon transverse energy ET>250 GeV from +-γ events and with ET>400 GeV from ννγ events are used to search for anomalous triple gauge-boson couplings ZZγ and Zγγ. The yields of events with diphoton invariant mass mγγ>200 GeV from +-γγ events and with mγγ>300 GeV from ννγγ events are used to search for anomalous quartic gauge-boson couplings ZZγγ and Zγγγ. No deviations from Standard Model predictions are observed and limits are placed on parameters used to describe anomalous triple and quartic gauge-boson couplings. © 2016 CERN, for the ATLAS Collaboration.

Department/s

  • Particle and nuclear physics
  • eSSENCE: The e-Science Collaboration

Publishing year

2016

Language

English

Publication/Series

Physical Review D - Particles, Fields, Gravitation and Cosmology

Volume

93

Issue

11

Document type

Journal article

Publisher

American Physical Society

Topic

  • Subatomic Physics

Status

Published

ISBN/ISSN/Other

  • ISSN: 1550-2368