$\mathrm{W}^+\mathrm{W}^-$ production and triple gauge boson couplings at LEP energies up to 183 GeV

The OPAL Collaboration: G. Abbiendi - et al.

doi:doi:10.1007/s100529901106

2021 Impact factor 4.991

Particles and Fields

Eur. Phys. J. C 8, 191-215
DOI 10.1007/s100529901106

$\mathrm{W^+W^-}$ production and triple gauge boson couplings at LEP energies up to 183 GeV

The OPAL Collaboration
G. Abbiendi² - et al.

²Dipartimento di Fisica dell' Università di Bologna and INFN, I-40126 Bologna, Italy

Received: 23 October 1998 / Published online: 1 March 1999

Abstract
A study of W-pair production in ${\rm e^+e^-}$ annihilations at LEP is presented, based on $877\,{\rm W^+W^-}$ candidates corresponding to an integrated luminosity of $57\,{\rm pb}^{-1}$ at $\sqrt s=183$ GeV. Assuming that the angular distributions of the W-pair production and decay, as well as their branching fractions, are described by the Standard Model, the W-pair production cross-section is measured to be $15.43\pm 0.61 ({\rm stat.}) \pm 0.26 ({\rm syst.})$ pb. Assuming lepton universality and combining with our results from lower centre-of-mass energies, the W branching fraction to hadrons is determined to be $67.9 \pm 1.2 ({\rm stat.})\pm 0.5 ({\rm syst.})$ %. The number of W-pair candidates and the angular distributions for each final state ( ${\rm q \bar q} \bar \ell \nu_\ell$ , ${\rm q \bar q q \bar q}, \bar \ell \nu_\ell \ell^\prime \bar \nu_{\ell^\prime })$ are used to determine the triple gauge boson couplings. After combining these values with our results from lower centre-of-mass energies we obtain $\Delta \kappa_\gamma = 0.11^{+0.52}_{-0.37}$ , $\Delta g^{\rm z}_1 = 0.01^{+ 0.13}_{-0.12}$ and $\lambda = -0.10^{+0.13}_{-0.12}$ ,where the errors include both statistical and systematic uncertainties and each coupling is determined by setting the other two couplings to the Standard Model value. The fraction of W bosons produced with a longitudinal polarisation is measured to be $0.242 \pm 0.091({\rm stat.}) \pm 0.023 ({\rm syst.})$ . All these measurements are consistent with the Standard Model expectations.