Measurements of CP-conserving Trilinear Gauge Boson Couplings WWV (V = gamma,Z) in e+e- Collisions at LEP2

TL;DR

This paper reports measurements of CP-conserving trilinear gauge boson couplings at LEP2, setting limits based on data from DELPHI, and confirms consistency with the Standard Model predictions.

Contribution

First precise limits on WWV couplings at LEP2 using multiple final states, improving previous DELPHI results and testing Standard Model predictions.

Findings

Limits on couplings are close to zero, consistent with Standard Model.

No evidence of anomalous gauge couplings observed.

Results improve upon previous measurements.

Abstract

The data taken by DELPHI at centre-of-mass energies between 189 and 209 GeV are used to place limits on the CP-conserving trilinear gauge boson couplings Delta_g1z, lambda_gamma and Delta_kappag associated to W+W- and single W production at LEP2. Using data from the jjlv, jjjj, jjX and lX final states, where j, l and X represent a jet, a lepton and missing four-momentum, respectively, the following limits are set on the couplings when one parameter is allowed to vary and the others are set to their Standard Model values of zero: Delta_g1z = -0.025^{+0.033}_{-0.030}, lambda_gamma = 0.002^{+0.035}_{-0.035} and Delta_kappag = 0.024^{+0.077}_{-0.081} . Results are also presented when two or three parameters are allowed to vary. All observations are consistent with the predictions of the Standard Model and supersede the previous results on these gauge coupling parameters published by DELPHI.