A study of W+W- events accompanied by hard photon radiation, Eγ > 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 < √s < 209 GeV. From the sample of 187 selected W+W-γ candidates with photon energies greater than 2.5 GeV, the W+W-γ cross-section is determined at five values of √s. 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(α) 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-γγ and W+W-Z0γ vertices: -0.020 GeV -2 < a0/∧2 < 0.020 GeV-2, -0.053 GeV-2 < ac/∧2 < 0.037 GeV -2, -0.16 GeV-2 < an/∧2 < 0.15 GeV-2, where ∧ represents the energy scale for new physics and a0, ac and an are dimensionless coupling constants.
|Number of pages||20|
|Journal||Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics|
|Publication status||Published - 2004 Jan 29|
ASJC Scopus subject areas
- Nuclear and High Energy Physics