QCD studies with e+e- annihilation data at 172-189 GeV

We have studied hadronic events from \(\mathrm{e^+e^-}\) annihilation data at centre-of-mass energies of \(\sqrt{s}=\)172, 183 and 189 GeV. The total integrated luminosity of the three samples, measured with the OPAL detector, corresponds to 250 pb\(^{-1}\). We present distributions of event shape variables, charged particlemultiplicity and momentum, measured separately in the three data samples. From these we extract measurements of the strong coupling \(\alpha_s \), the mean charged particlemultiplicity \(\langle n_{\mathrm{ch}}\rangle\) and the peak position \(\xi_0\) in the \(\xi_p=\ln(1/x_p)\) distribution. In general the data are described well by analytic QCD calculations and Monte Carlo models. Our measured values of \(\alpha_s \), \(\langle n_{\mathrm{ch}}\rangle\) and \(\xi_0\) are consistent with previous determinations at \(\sqrt{s}=M_{\mathrm{Z^0}}\).