Energy Scan of the e+e- →hb (nP)π+π- (n=1, 2) Cross Sections and Evidence for Y(11020) Decays into Charged Bottomoniumlike States

Abstract

Using data collected with the Belle detector at the KEKB asymmetric-energy e+e- collider, we measure the energy dependence of the e+e-→hb(nP)π+π- (n=1, 2) cross sections from thresholds up to 11.02 GeV. We find clear (10860) and (11020) peaks with little or no continuum contribution. We study the resonant substructure of the (11020)→hb(nP)π+π- transitions and find evidence that they proceed entirely via the intermediate isovector states Zb(10610) and Zb(10650). The relative fraction of these states is loosely constrained by the current data: The hypothesis that only Zb(10610) is produced is excluded at the level of 3.3 standard deviations, while the hypothesis that only Zb(10650) is produced is not excluded at a significant level.