Observation of the $J/\ddot{I}ˆ$ and $\ddot{I}ˆ(3686)$ decays into $\hat{I}\cdot \hat{I}{\pounds }^{+}\bar{\hat{I}}{\pounds }^{-}$

Abstract

The decays $J/\ddot{I}ˆ\to \hat{I}\cdot \hat{I}{\pounds }^{+}\bar{\hat{I}}\pounds {}^{-}$ and $\ddot{I}ˆ(3686)\to \hat{I}\cdot \hat{I}{\pounds }^{+}\bar{\hat{I}}\pounds {}^{-}$ are observed for the first time, using $(10087\pm 44)\times 10^6$ $J/\ddot{I}ˆ$ and $(448.1\pm 2.9)\times 10^6$ $\ddot{I}ˆ(3686)$ events collected with the BESIII detector at the BEPCII collider. We determine the branching fractions of these two decays to be $\mathcal{B}(J/\ddot{I}ˆ\to \hat{I}\cdot \hat{I}{\pounds }^{+}\bar{\hat{I}}\pounds {}^{-})=(6.34\pm 0.21\pm 0.37)\times 10^{-5}$ and $\mathcal{B}(\ddot{I}ˆ(3686)\to \hat{I}\cdot \hat{I}{\pounds }^{+}\bar{\hat{I}}\pounds {}^{-})=(9.59\pm 2.37\pm 0.61)\times 10^{-6}$, where the first uncertainties are statistical and the second are systematic. The ratio of these two branching fractions is determined to be $\frac{\mathcal{B}(\ddot{I}ˆ(3686)\to \hat{I}\cdot \hat{I}{\pounds }^{+}\bar{\hat{I}}\pounds {}^{-})}{\mathcal{B}(J/\ddot{I}ˆ\to \hat{I}\cdot \hat{I}{\pounds }^{+}\bar{\hat{I}}\pounds {}^{-})}=(15.1\pm 3.8)\%$, which is in agreement with the "12\% rule."

9 pages and 10 figures