Measurement of C-Parameter and Determination of αs from C-Parameter and Jet Broadening at PETRA Energies

e+e− annihilation data recorded by the JADE detector at PETRA were used to measure the C-parameter for the first time at √ s = 35 and 44 GeV. The distributions were compared to a resummed QCD calculation which recently became available for this observable. In addition, we applied extended resummed calculations to the heavy and wide jet broadening variables, BT and BW , which now include a proper treatment of the quark recoil against multi-gluon emission with single-logarithmic accuracy. We further investigated power corrections to the mean values of the observables mentioned above. In this study, we considered all available e+e− data between √ s = 35 and 172 GeV. (1) III. Physikalisches Institut der RWTH Aachen, D-52056 Aachen, Germany contact e-mail: [email protected] (2) for a full list of members of the JADE Collaboration see Reference [1]