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A study of W+W-gamma events at LEP

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  • G Abbiendi
  • C Ainsley
  • P F Akesson
  • G Alexander
  • J Allison
  • P Amaral
  • G Anagnostou
  • K J Anderson
  • S Arcelli
  • S Asai
  • D Axen
  • G Azuelos
  • I Bailey
  • E Barberio
  • R J Barlow
  • R J Batley
  • P Bechtle
  • T Behnke
  • K W Bell
  • P J Bell
  • G Bella
  • A Bellerive
  • G Benelli
  • S Bethke
  • O Biebel
  • O Boeriu
  • P Bock
  • M Boutemeur
  • S Braibant
  • L Brigliadori
  • R M Brown
  • K Buesser
  • H J Burckhart
  • S Campana
  • R K Carnegie
  • B Caron
  • A A Carter
  • J R Carter
  • C Y Chang
  • D G Charlton
  • A Csilling
  • M Cuffiani
  • S Dado
  • A De Roeck
  • E A De Wolf
  • K Desch
  • B Dienes
  • M Donkers
  • J Dubbert
  • L Kormos
  • OPAL Collaboration
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<mark>Journal publication date</mark>29/01/2004
<mark>Journal</mark>Physics Letters B
Issue number1-2
Volume580
Number of pages20
Pages (from-to)17-36
Publication StatusPublished
<mark>Original language</mark>English

Abstract

A study of W+W- events accompanied by hard photon radiation, Egamma > 2.5 GeV, produced in e(+)e(-) collisions at LEP is presented. Events consistent with being two on-shell W-bosons and an isolated photon are selected from 681 pb(-1) of data recorded at 180 GeV < roots < 209 GeV. From the sample of 187 selected W(+)W(-)gamma candidates with photon energies greater than 2.5 GeV, the W(+)W(-)gamma cross-section is determined at five values of roots. The results are consistent with the Standard Model expectation. Averaging over all energies, the ratio of the observed cross-section to the Standard Model expectation is

R(data/SM) = 0.99 +/- 0.09 +/- 0.04,

where the errors represent the statistical and systematic uncertainties respectively. These data provide constraints on the related O(alpha) systematic uncertainties on the measurement of the W-boson mass at LEP. Finally, the data are used to derive 95% confidence level upper limits on possible anomalous contributions to the W(+)W(-)gammagamma and W(+)W(-)Z(0)y vertices:

-0.020 GeV-2 < a(0)/Lambda(2) < 0.020 GeV-2,

-0.053 GeV-2 < a(c)/Lambda(2) < 0.037 GeV-2,

-0.16 GeV-2 < a(n)/Lambda(2) < 0.15 GeV-2,

where Lambda represents the energy scale for new physics and a(0), a(c) and a(n) are dimensionless coupling constants. (C) 2003 Elsevier B.V. All rights reserved.