Observation of two charged bottomonium-like resonances
We report the observation of two narrow structures at 10610 MeV/c 2 and 10650 MeV/c2 in the π ±γ(nS) (n = 1,2,3) and π±hb(mP) (m = 1,2) mass spectra that are produced in association with a single charged pion in γ(5S) decays. The measured masses and widths of the two structures averaged over the five final states are M1 = 10608.4 ± 2.0MeV/c2, γ1 = 15.6 ± 2.5 MeV and M 2 = 10653.2 ± 1.5 MeV/c2, γ2 = 14.4 ±3.2 MeV. Analysis favors quantum numbers of IG(J P)=1+(1+) for both states. The results are obtained with a 121.4 fb-1 data sample collected with the Belle detector near the γ(5S) resonance at the KEKB asymmetric-energy e+e- collider.