Two-Particle Angular Correlations in e+e- Interactions compared with QCD Predictions

Two-particle angular correlations in jet cones have been measured in e+e− annihilation into hadrons at LEP energies (View the MathML source 91 and 183 GeV) and are compared with QCD predictions using the LPHD hypothesis. Two different functions have been tested. While the differentially normalized correlation function shows substantial deviations from the predictions, a globally normalized correlation function agrees well. The size of αSeff (and other QCD parameters) and its running with the relevant angular scale, the validity of LPHD, and problems due to non-perturbative effects are discussed critically.