Energy Scan of the $e^{+}{e}^{-}\to h_b\left(nP\right){\pi }^{+}{\pi }^{-}$ ($n=1$ , 2) Cross Sections and Evidence for ${\rm Y}\left(11020\right)$ Decays into Charged Bottomoniumlike States

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