Observation of Two Charged Bottomoniumlike Resonances inΥ(5S)Decays

Abstract

We report the observation of two narrow structures in the mass spectra of the ${\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\Upsilon}(nS)$ ($n=1$, 2, 3) and ${\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}{h}_{b}(mP)$ ($m=1$, 2) pairs that are produced in association with a single charged pion in $\ensuremath{\Upsilon}(5S)$ decays. The measured masses and widths of the two structures averaged over the five final states are ${M}_{1}=(10\text{ }607.2\ifmmode\pm\else\textpm\fi{}2.0)\text{ }\text{ }\mathrm{MeV}/{c}^{2}$, ${\ensuremath{\Gamma}}_{1}=(18.4\ifmmode\pm\else\textpm\fi{}2.4)\text{ }\text{ }\mathrm{MeV}$, and ${M}_{2}=(10\text{ }652.2\ifmmode\pm\else\textpm\fi{}1.5)\text{ }\text{ }\mathrm{MeV}/{c}^{2}$, ${\ensuremath{\Gamma}}_{2}=(11.5\ifmmode\pm\else\textpm\fi{}2.2)\text{ }\text{ }\mathrm{MeV}$. The results are obtained with a $121.4\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ data sample collected with the Belle detector in the vicinity of the $\ensuremath{\Upsilon}(5S)$ resonance at the KEKB asymmetric-energy ${e}^{+}{e}^{\ensuremath{-}}$ collider.