Measurement of Branching Fractions of $J/\ddot{I}ˆ$ and $\ddot{I}ˆ(3686)$ decays to $\hat{I}{\pounds }^{+}$ and $\overline{\hat{I}}{\pounds }^{-}$

Abstract

Using $1310.6\times 10^6$ $J/\ddot{I}ˆ$ and $448.1\times 10^6$ $\ddot{I}ˆ(3686)$ events collected with the BESIII detector, the branching fractions of $J/\ddot{I}ˆ$ and $\ddot{I}ˆ(3686)$ decays to $\hat{I}{\pounds }^{+}\overline{\hat{I}}{\pounds }^{-}$ are measured to be $(10.61\pm 0.04\pm 0.36)\times 10^{-4}$ and $(2.52\pm 0.04\pm 0.09)\times 10^{-4}$, respectively. In addition, the ratio of $\mathcal{B}(\ddot{I}ˆ(3686)\to \hat{I}{\pounds }^{+}\overline{\hat{I}}{\pounds }^{-})/\mathcal{B}(J/\ddot{I}ˆ\to \hat{I}{\pounds }^{+}\overline{\hat{I}}{\pounds }^{-})$ is determined to be $(23.8\pm 1.1)\%$ which violates the "$12\%$ rule".