The Anomalous Υ(1s)π+π− and Υ(2s)π+π− Production near the Υ(5s) Resonance
نویسنده
چکیده
We report the study of ee → Υ(1S)ππ, Υ(2S)ππ, Υ(3S)ππ, and Υ(1S)KK, near the peak of the Υ(5S) resonance. The results are based on a data sample of 21.7 fb collected with the Belle detector at the KEKB ee collider. Attributing the signals to the Υ(5S) resonance, the partial widths Γ(Υ(5S) → Υ(1S)ππ) = 0.59± 0.04(stat)± 0.09(syst) MeV and Γ(Υ(5S) → Υ(2S)ππ) = 0.85 ± 0.07(stat) ± 0.16(syst) MeV are obtained from the observed cross sections. These values exceed by more than two orders of magnitude the previously measured partial widths for dipion transitions between lower Υ resonances.
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