Precise measurement of the branching fractions of $J/\ddot{I}ˆ\to \bar{\hat{I}}›\ddot{I}{€}^{+}\hat{I}{\pounds }^{-}+c.c.$ and $J/\ddot{I}ˆ\to \bar{\hat{I}}›\ddot{I}{€}^{-}\hat{I}{\pounds }^{+}+c.c.$

Abstract

Based on a data sample of $(10087\pm 44)\times 10^6$ $J/\ddot{I}ˆ$ events collected with the BESIII detector, the branching fraction of $J/\ddot{I}ˆ\to \bar{\hat{I}}›\ddot{I}{€}^{+}\hat{I}{\pounds }^{-}+c.c.$ is measured to be $(1.221\pm 0.002\pm 0.038)\times 10^{-3}$, and the branching fraction of its isospin partner mode $J/\ddot{I}ˆ\to \bar{\hat{I}}›\ddot{I}{€}^{-}\hat{I}{\pounds }^{+}+c.c.$ is measured to be $(1.244\pm 0.002\pm 0.045)\times 10^{-3}$ with improved precision. Here the first uncertainties are statistical and the second ones systematic. The isospin symmetry of the $\hat{I}\pounds$ baryon in charmonium hadronic decay and the "$12\%$ rule" are tested, and no violation is found. The potential of using these channels as $\hat{I}\pounds$ baryon sources for nuclear physics research is studied, and the momentum and angular distributions of these sources are provided.