Measurement of triple gauge boson couplings from ${\rm W^+W^-}$ production at $\sqrt s=172$GeV

Abstract.

We present measurements of triple gauge boson coupling parameters using data recorded by the OPAL detector at LEP2, at a centre-of-mass energy of 172 GeV. A total of 120 W-pair candidates has been selected in the ${\rm q \bar q q \bar q}$, ${\rm q\bar q} \ell \bar\nu_\ell$ and $\ell \bar \nu_\ell \bar\ell^\prime \nu_{\ell^\prime }$ decay channels, for an integrated luminosity of 10.4 pb$^{-1}$. We use these data to determine several different anomalous coupling parameters using the measured cross-section and the distributions of kinematic variables. We measure $\alpha_{B\phi} = 0.35^{+1.29}_{-1.07} \pm 0.38$, $\alpha_{W\phi} = 0.00^{+0.30}_{-0.28} \pm 0.11$, $\alpha_W = 0.18^{+0.49}_{-0.47} \pm 0.23$, $\Delta g^{\rm z}_1 = -0.03^{+0.40}_{-0.37} \pm 0.14$, $\Delta\kappa_\gamma ^{(HISZ)} = 0.03^{+0.55}_{-0.51} \pm 0.20$, and $\Delta \kappa = 0.33^{+0.49}_{-0.46} \pm 0.21$. Combining the $\alpha_{W\phi}$ result with our previous result obtained from the 161 GeV data sample we measure $\alpha_{W\phi} = -0.08^{+0.28}_{-0.25} \pm 0.10$. All of these measurements are consistent with the Standard Model.