The ϒ′ state has been observed as a narrow resonance at M ( ϒ ′) = 10.02 ± 0.02 GeV in e + e − annihilations, using a NaI and lead-glass detector in the DORIS storage ring at DESY. The ratio Г ee Г had /Г tot of electronic, hadronic, and total widths has been measured to be 0.32 ± 0.13 keV. The parameters of the Г particle have also been determined to be/ M (Г)
We report on a high precision measurement of ϕ-meson production in continuum events and in direct decays of the Υ(1S)- and Υ(2S)-mesons. The ratio of the total production rate of ϕ-mesons in direct Υ(1S)- and Υ(2S)-decays over that in continuum events is 1.32±0.08±0.09 and 1.07±0.13±0.11 respectively. This is compatible with the corresponding ratio obtained for lighter mesons, but is appreciably smaller than the relative baryon production rate.
The total cross section fore+e− annihilation into hadrons for center of mass energies from 9.4 to 9.5 GeV has been measured with the nonmagnetic DESY-Heidelberg detector at DORIS. A value ofR=σhad/σµµ=3.8±0.7 for the continuum region around the Υ (9.46) resonance has been determined. The ratioΓeeΓhad/Γtot of electronic, hadronic and total widths has been reevaluated to be (1.00±0.23) keV for the Υ resonance and (0.37±0.16) keV for the Υ′. In addition, a search for directly produced pohotons from Υ decays of the type Υ→γ+gluon+gluon has been performed. The Υ decay into muon pairs has also been searched for.
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