The decay of the upsilon into photons and gluons

The hadronic decays of heavy quark-antiquark 13S1 resonances such as the psi/J or UPSILON can provide an ideal laboratory for studying the properties of gluon jets. The predictions of QCD perturbation theory for gluon-jet structures, hadronic multiplicities, fragmentation distributions, and angular distributions are discussed. In particular the channel (Qanti Q)→γ+X, whose rate, spectrum, and angular distribution are predicted in lowest order, should allow the study of the jet and resonance structure produced via two intermediate gluons. (Auth.)