The triple gauge-boson couplings involving the W are determined using data samples collected with the ALEPH detector at mean centre-of-mass energies of 183 GeV and 189 GeV, corresponding to integrated luminosities of 57 pb^-1 and 174 pb^-1, respectively. The couplings, g^Z_1, Kappa_gamma and lambda_gamma, are measured using W-pair events, single-W production and single-gamma production. Each coupling is measured individually with the other two coupling fixed at their Standard Model value. Including ALEPH results from lower energies, the 95% confidence level intervals for the deviation to the Standard Model are -0.087 < Dg^Z_1 < 0.141 -0.200 < DKappa_gamma < 0.258 -0.062 < Lambda_gamma < 0.147. Fits are also presented where two or all three couplings are allowed to vary. In addition, W-pair events are used to set limits on the C- or P-violating couplings g^V_4, g^V_5, Kappa_V, and Lambda_V, where V denotes either gamma or Z. No deviations from the Standard Model expectations are observed.
The errors included the statistical and systematic uncertainties. Deviation from SM values.
The errors included the statistical and systematic uncertainties. Combined results, lower sqrt(s) data are also included.
The errors included the statistical and systematic uncertainties. Combined results, lower sqrt(s) data are also included. Three-parameter fit.
Measurements of the trilinear gauge boson couplings WWgamma and WWZ are presented using the data taken by DELPHI in 1998 at a centre-of-mass energy of 189 GeV and combined with DELPHI data at 183 GeV. Values are determined for Delta(g_1^Z) and Delta(kappa_gamma), the differences of the WWZ charge coupling and of the WWgamma dipole coupling from their Standard Model values, and for lambda_gamma, the WWgamma quadrupole coupling. A measurement of the magnetic dipole and electric quadrupole moment of the W is extracted from the results for Delta(kappa_gamma) and lambda_gamma. The study uses data from the final states jjlv, jjjj, lX, jjX and gammaX, where j represents a quark jet, l an identified lepton and X missing four-momentum. The observations are consistent with the predictions of the Standard Model.
No description provided.
Single W boson production in electron-positron collisions is studied with the L3 detector at LEP. The data sample collected at a centre-of-mass energy of \sqrt{s} = 188.7GeV corresponds to an integrated luminosity of 176.4pb^-1. Events with a single energetic lepton or two acoplanar hadronic jets are selected. Within phase-space cuts, the total cross-section is measured to be 0.53 +/- 0.12 +/- 0.03 pb, consistent with the Standard Model expectation. Including our single W boson results obtained at lower \sqrt{s}, the WWgamma gauge couplings kappa_gamma and lambda_gamma are determined to be kappa_gamma = 0.93 +/- 0.16 +/- 0.09 and lambda_gamma = -0.31 +0.68 -0.19 +/- 0.13.
No description provided.
No description provided.
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The cross-sections for the production of single charged and neutral intermediate vector bosons were measured using integrated luminosities of 52 pb^{-1} and 154 pb^{-1} collected by the DELPHI experiment at centre-of-mass energies of 182.6 GeV and 188.6 GeV, respectively. The cross-sections for the reactions were determined in limited kinematic regions. The results found are in agreement with the Standard Model predictions for these channels.
Cross sections for single-W production in the (E- NUEBAR Q QBAR + CC) and (E- NUEBAR LEPTON LEPTONBAR) + CC) channels.
Cross sections for the E NU E NU channel, which includes contributions from both single-W and from single-Z0 with a large interference bewteen the two processes.
Cross sections for single-Z0 production in the hadronic channel.
Single W production is studied in the data recorded with the ALEPH detector at LEP at centre-of-mass energies between 161 and 183 GeV. The cross section is measured to be σ W =0.41±0.17(stat.)±0.04(syst.) pb at 183 GeV, consistent with the Standard Model expectation. Limits on non-standard WW γ couplings are deduced as −1.6<κ γ <1.5 (λ γ =0) and −1.6<λ γ <1.6 (κ γ =1) at 95% C.L. A search for effectively invisible decays of the W boson in W pair production is performed, leading to an upper limit on the branching ratio of 1.3% ( Γ inv =27 MeV ) at 95% C.L.
No description provided.
We report on a study of single W boson production in a data sample collected by the L3 detector at centre-of-mass energies from 130 to 183 GeV. The signal consists of large missing energy final states with a single energetic lepton or two hadronic jets. The measured cross sections at five different centre-of-mass energies are consistent with the Standard Model expectations. The following limits on the anomalous WW γ gauge couplings are derived at 95% CL: −0.46< Δκ γ <0.57 and −0.86< λ γ <0.75.
The absence of the negative-side statistical error indicate that zero signal cross section is not excluded at 68% CL.
Cross sections from overall fit to all processes at 183 GeV.
We report on the observation of single W boson production in a data sample collected by the L3 detector at LEP2. The signal consists of large missing energy final states with a single energetic lepton or two hadronic jets. The cross-section is measured to be 0.61 −0.33 +0.43 ± 0.05 pb at the centre of mass energy s = 172 GeV , consistent with the Standard Model expectation. From this measurement the following limits on the anomalo γWW gauge couplingsare derived at 95% CL: −3.6 < Δκ γ < 1.5 and −3.6 < λ γ < 3.6.
No description provided.
No description provided.
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