Measurements of the e + e~ cross section above BB threshold are reported. Structures are observed which could be the Y(5S) and Y(6S) resonances. The masses and widths are given and compared with various potential-model predictions. Average charged multiplicities and inclusive lepton yields are also presented.

A detailed investigation of the decay Y(2S)-+.rr+.rr-T( IS) has been made from 128 000 Y ( 2 S ) decays observed in the CLEO detector at the Cornell Electron Storage Ring (CESR). We find this branching ratio to be (19.1rtl.2rtO.6)%. The properties of the rrr system have been studied using 491 exclusive events of the type T (ZS)+r+.rr-T( IS), Y ( 1 S ) + e + e P or p + p -. Assuming e-p universality we find B ( T ( l S ) + p + p -) =(2.84+.0.18+.0.20)%. A search for Y ( 2 S ) + r ] Y ( 1s) yieldsan upper limit of 1% at the 90% confidence level for this branching ratio. We have also searched for [ Y ( 2 S ) or Y ( 3S)]+rr+.rr-Y( IS), Y ( lS)+noninteracting particles.

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We have observed decays of the Y(15) into hadronic final states containing high-energy photons. These are interpreted as coming from the decay Y(15)-> y + gluon+gluon. We compare the shape of the observed photon energy spectrum with several theoretical predictions and deduce the value of the strong-coupling constant a s and the QCD scale parameter Aj^ (MS denotes the modified minimal-subtraction scheme) associated with each prediction.PACS numbers: 13.40.Hq, 12.38.Qk, 14.40.GxThe theory of quantum chromodynamics (QCD) predicts the decay of quarkonium into a photon and two gluons. Predictions have been made for the branching ratio, photon energy spectrum, and photon angular distribution. To lowest order this decay is identical to the dominant decay mode, that into three gluons, except for the re-1222

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