Observation of an enhancement in e+e- to Upsilon(1S)pi+pi-, Upsilon(2S)pi+pi-, and Upsilon(3S)pi+pi- production near sqrt{s}=10.89 GeV at Belle

Abstract

We measure the production cross sections for e+e- -> Upsilon(1S)pi+pi-, Upsilon(2S)pi+pi-, and Upsilon(3S)pi+pi- as a function of sqrt{s} between 10.83 GeV and 11.02 GeV. The data consists of 8.1 fb^-1 collected with the Belle detector at the KEKB e+e- collider. We observe enhanced production in all three final states that does not agree well with the conventional Upsilon(10860) lineshape. A fit using a Breit-Wigner resonance shape yields a peak mass of [10888.4 +2.7/-2.6 (stat) +- 1.2 (syst)] MeV/c^2 and a width of [30.7 +8.3/-7.0 (stat) +- 3.1 (syst)] MeV/c^2.