We have studied hadronic events from 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 particle multiplicity and momentum, measured separately in the three data samples. From these we extract measurements of the strong coupling alpha_s, the mean charged particle multiplicity <nch> 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, <nch> and xi_0 are consistent with previous determinations at sqrt{s}=MZ.
Distribution of Thrust.
Distribution of Thrust Major.
Distribution of Thrust Minor.
The charged particle multiplicity distribution for e + e − annihilations at s = 29 GeV has been measured using the High Resolution Spectrometer at PEP. The multiplicity distribution, expressed as a function of the mean, shows KNO scaling when compared to e + e − data at other energies. Multiplicity distributions for particles selected in different central rapidity spans are presented. All of these are well presented by the Negative binomial distribution. As the rapidity span is narrowed, the distributions become broader and approach a constant value of the parameter k .
KNO charged multiplicity distributions for the Inclusive Data Sample. The numerical values are calculated from the multiplicity distributions given in Derrick et al., PR D34,3304.
Folded rapidity distribution measured along the thrust axis of the event. Errors are dominated by systematics. All charged particles are assigned the pion mass.
KNO charged multiplicity distribution for the Two Jet Data Sample. The numerical values are calculated from the multiplicity distributions given in Derrick et al., PR D34,3304.
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