Measurement of triple gauge-boson couplings at LEP energies up to 189 GeV

Abstract

Abstract.

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-{\it W} production and single-\(\gamma\) production. Each coupling is measured individually with the other two couplings 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

\(-0.087 <\Delta{g}^{Z}_1 < 0.141\), \(-0.200 < \Delta\kappa_\gamma < 0.258\), and \(-0.062 < \lambda_\gamma < 0.147\).

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 \(g^V_4\), \(g^V_5\), \({\tilde{\kappa}_{V}}\), and \({\tilde{\lambda}_{V}}\), where V denotes either \(\gamma\) or Z. No deviations from the standard model expectations are observed.