Jet structure and tests of quantum chromodynamics with the MARK-J at PETRA

The analysis of the spatial energy distribution of hadronic jet events produced in e+e- annihilation, which has been performed by the MARK-J Collaboration at PETRA is presented. The quantity ''oblateness'' is defined to characterize the flat shape of the energy configuration, and the flat events show an unambigous three-jet structure. The rate of flat events and the distribution of oblateness are in excellent agreement with the predictions of a phenomenological model based on quantum chromodynamics, demonstrating that the data can be naturally described by the production of quark-antiquark pairs accompanied by hard non-collinear gluons. The relative yield and the shape distribution of the three-jet events has been used to determine the strong coupling constant αsub(s) in the region √s approximately 30 GeV. We find αsub(s) = 0.23+-0.02 ( statistical error) with a systematic error of +-0.04