Measurement of Branching Fractions of $\ddot{I}ˆ(3686)\to \ddot{I}•\hat{I}{\cdot }^{\prime },\ddot{I}•f_1(1285)$ and $\ddot{I}•\hat{I}\cdot (1405)$

Abstract

Using a sample of $448.1\times 10^6$ $\ddot{I}ˆ(3686)$ events collected with the BESIII detector, we perform a study of the decay $\ddot{I}ˆ(3686)\to \ddot{I}•\ddot{I}{€}^{+}\ddot{I}{€}^{-}\hat{I}\cdot$. The branching fraction of $\ddot{I}ˆ(3686)\to \ddot{I}•\hat{I}{\cdot }^{\prime }$ is determined to be $(1.51\pm 0.16\pm 0.12)\times 10^{-5}$, which is consistent with the previous measurement but with significantly improved precision. The resonances $f_1(1285)$ and $\hat{I}\cdot (1405)$ are clearly observed in the $\ddot{I}{€}^{+}\ddot{I}{€}^{-}\hat{I}\cdot$ mass spectrum with statistical significances of $18\ddot{I}ƒ$ and $9.7\ddot{I}ƒ$, respectively. The corresponding product branching fractions are measured to be $\mathcal{B}(\ddot{I}ˆ(3686)\to \ddot{I}•f_1(1285),f_1(1285)\to \ddot{I}{€}^{+}\ddot{I}{€}^{-}\hat{I}\cdot )=(1.03\pm 0.10\pm 0.09)\times 10^{-5}$ and $\mathcal{B}(\ddot{I}ˆ(3686)\to \ddot{I}•\hat{I}\cdot (1405),\hat{I}\cdot (1405)\to \ddot{I}{€}^{+}\ddot{I}{€}^{-}\hat{I}\cdot )=(8.46\pm 1.37\pm 0.92)\times 10^{-6}$.