Observation of $\hat{I}{\cdot }^{\prime }\to \ddot{I}{€}^{+}\ddot{I}{€}^{-}\hat{I}{¼}^{+}\hat{I}{¼}^{-}$

Abstract

Using $(1310.6\pm 7.0)\times 10^{6}J/\ddot{I}ˆ$ events acquired with the BESIII detector at the BEPCII storage rings, the decay $\hat{I}{\cdot }^{\prime }\to \ddot{I}{€}^{+}\ddot{I}{€}^{-}\hat{I}{¼}^{+}\hat{I}{¼}^{-}$ is observed for the first time with a significance of 8$\ddot{I}ƒ$ via the process $J/\ddot{I}ˆ\to {\hat{I}}^3\hat{I}{\cdot }^{\prime }$. We measure the branching fraction of $\hat{I}{\cdot }^{\prime }\to \ddot{I}{€}^{+}\ddot{I}{€}^{-}\hat{I}{¼}^{+}\hat{I}{¼}^{-}$ to be $\mathcal{B}(\hat{I}{\cdot }^{\prime }\to \ddot{I}{€}^{+}\ddot{I}{€}^{-}\hat{I}{¼}^{+}\hat{I}{¼}^{-})$=(1.97$\pm$0.33(stat.)$\pm$0.18(syst.))$\times 10^{-5}$, where the first and second uncertainties are statistical and systematic, respectively.