Observation of $\ddot{I}{‡}_{c0}\to \hat{I}{\pounds }^{+}\bar{\hat{I}}{\pounds }^{-}\hat{I}\cdot$ and evidence for $\ddot{I}{‡}_{c1,2}\to \hat{I}{\pounds }^{+}\bar{\hat{I}}{\pounds }^{-}\hat{I}\cdot$

Abstract

Using $(27.12\pm 0.14)\times 10^8$ $\ddot{I}ˆ(3686)$ events collected with the BESIII detector, the decay $\ddot{I}{‡}_{c0}\to \hat{I}{\pounds }^{+}\bar{\hat{I}}{\pounds }^{-}\hat{I}\cdot$ is observed for the first time with a statistical significance of $7.0\ddot{I}ƒ$, and evidence for $\ddot{I}{‡}_{c1}\to \hat{I}{\pounds }^{+}\bar{\hat{I}}{\pounds }^{-}\hat{I}\cdot$ and $\ddot{I}{‡}_{c2}\to \hat{I}{\pounds }^{+}\bar{\hat{I}}{\pounds }^{-}\hat{I}\cdot$ is found with statistical significances of $4.3\ddot{I}ƒ$ and $4.6\ddot{I}ƒ$, respectively. The branching fractions are determined to be $\mathcal{B}(\ddot{I}{‡}_{c0}\to \hat{I}{\pounds }^{+}\bar{\hat{I}}{\pounds }^{-}\hat{I}\cdot )=(1.26\pm 0.20\pm 0.13)\times 10^{-4},\mathcal{B}(\ddot{I}{‡}_{c1}\to \hat{I}{\pounds }^{+}\bar{\hat{I}}{\pounds }^{-}\hat{I}\cdot )=(5.10\pm 1.21\pm 0.67)\times 10^{-5}$, and $\mathcal{B}(\ddot{I}{‡}_{c2}\to \hat{I}{\pounds }^{+}\bar{\hat{I}}{\pounds }^{-}\hat{I}\cdot )=(5.46\pm 1.18\pm 0.50)\times 10^{-5}$, where the first uncertainties are statistical, and the second ones are systematic.