Observation of $\ddot{I}ˆ(3686)\to 3\ddot{I}•$

Abstract

Using $(2.712\pm 0.014)\times 10^9$ $\ddot{I}ˆ(3686)$ events collected by the BESIII detector operating at the BEPCII collider, we report the first observation of $\ddot{I}ˆ(3686)\to 3\ddot{I}•$ decay with a significance larger than 10$\ddot{I}ƒ$. The branching fraction of this decay is determined to be $(1.46\pm 0.05\pm 0.17)\times 10^{-5}$, where the first uncertainty is statistical and the second is systematic. No significant structure is observed in the $\ddot{I}•\ddot{I}•$ invariant mass spectra.