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

TL;DR

This study measures the production rates of specific bottomonium states in electron-positron collisions near 10.89 GeV, revealing an unexpected enhancement inconsistent with the known Upsilon(10860) resonance.

Contribution

It reports the observation of an enhancement in Upsilon pi+pi- production near 10.89 GeV, suggesting a possible new resonance or state beyond the conventional Upsilon(10860).

Findings

Enhanced production observed in all three final states.

Resonance fit indicates a peak at approximately 10.89 GeV.

Measured width of the enhancement is about 30.7 MeV.

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.