2007/10/31 by The Belle Collaboration, K. -F. Chen, W. -S. Hou +2 · 1 citation
Physics and Astronomy · #hep-ex
paper · pdf · doi:10.1103/physrevlett.100.112001
published as Phys.Rev.Lett.100:112001,2008 · 6 pages, 4 figures, submit to PRL
arxiv created 2009/10/26 · arxiv updated 2009/12/01
We report the first observation of e+e- -> Upsilon(1S)pi+pi-, Upsilon(2S)pi+pi-, and first evidence for e+e- -> Upsilon(3S)pi+pi-, Upsilon(1S)K+K-, near the peak of the Upsilon(5S) resonance at sqrts~10.87 GeV. The results are based on a data sample of 21.7 fb-1 collected with the Belle detector at the KEKB e+e- collider. Attributing the signals to the Upsilon(5S) resonance, the partial widths Gamma(Upsilon(5S) -> Upsilon(1S) pi+pi-) = 0.59 +- 0.04 (stat) +- 0.09 (syst) MeV and Gamma(Upsilon(5S) -> Upsilon(2S) pi+pi-) = 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 Upsilon resonances.