A study of the orientation and energy partition of three-jet events in   hadronic Z0 decays
  We have measured the distributions of the jet energies in e+e- --> qq^bar g events, and of the three orientation angles of the event plane, using hadronic $Z^0$ decays collected in the SLD experiment at SLAC. We find that the data are well described by perturbative QCD incorporating vector gluons. We have also compared our data with models of scalar and tensor gluon production, and discuss limits on the relative contributions of these particles to three-jet production in e+e- annihilation. 
K. Abe, et al. (The SLD collaboration)