Observation of the ${\rm Y}(1^3{D}_J)$ Bottomonium State through Decays to ${\pi }^{+}{\pi }^{-}{\rm Y}(1S)$

Abstract

Based on $122\times 10^6$ \ThreeS events collected with the \babar\ detector, we have observed the \OneDJ bottomonium state through the $\text{ThreeS}\to \text{g}\text{g}\text{OneDJ}\to \text{g}\text{g}\text{pip}\text{pim}\text{OneS}$ decay chain.The significance for the $J=2$ member of the \OneDJ triplet is 5.8 standard deviations including systematic uncertainties.The mass of the $J=2$ state is determined to be $10164.5\pm 0.8(stat.)\pm 0.5(syst.)$~\mevcc.We use the $\text{pip}\text{pim}$ invariant mass distribution to confirm the consistency of the observed state with the orbital angular momentum assignment of the \OneDJ.

Comments: 8 pages, 3 figures, Physical Reviews D 82, 111102(R) (2010)