Measurement of W gamma and Z gamma production in pp collisions at root s=7 TeV

Chatrchyan S., Khachatryan V., Sirunyan A. M. , Tumasyan A., Adam W., Bergauer T., ...More

PHYSICS LETTERS B, vol.701, no.5, pp.535-555, 2011 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 701 Issue: 5
  • Publication Date: 2011
  • Doi Number: 10.1016/j.physletb.2011.06.034
  • Title of Journal : PHYSICS LETTERS B
  • Page Numbers: pp.535-555


A measurement of W gamma and Z gamma production in proton-proton collisions at root s = 7 TeV is presented. Results are based on a data sample recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 36 pb(-1). The electron and muon decay channels of the W and Z are used. The total cross sections are measured for photon transverse energy E-T(gamma) > 10 GeV and spatial separation from charged leptons in the plane of pseudorapidity and azimuthal angle Delta R(l.gamma) > 0.7, and with an additional dilepton invariant mass requirement of M-ll > 50 GeV for the Z gamma process. The following cross section times branching fraction values are found: sigma(pp -> W gamma + X) x B(W -> lv) = 56.3 +/- 5.0(stat.) +/- 5.0(syst.) +/- 2.3(lumi.) pb and sigma(pp -> Z gamma + X) x B(Z -> ll) = 9.4 +/- 1.0(stat.) +/- 0.6(syst.) +/- 0.4(lumi.) pb. These measurements are in agreement with standard model predictions. The first limits on anomalous WW gamma, ZZ gamma, and Z gamma gamma trilinear gauge couplings at root s = 7 TeV are set. (C) 2011 CERN. Published by Elsevier B.V. All rights reserved.