Observation of $J/ψ\rightarrow\barΛπ^{+}Σ^{-}+c.c.$ and precise measurement of branching fraction of $J/ψ\rightarrow\barΛπ^{-}Σ^{+}+c.c.$

Based on a data sample of $(10087\pm44)\times10^{6}$ $J/ψ$ events collected with the BESIII detector, the process of $J/ψ\rightarrow\barΛπ^{+}Σ^{-}+c.c.$ is observed for the first time and the branching fraction is measured to be $(1.224\pm 0.002\pm0.034)\times10^{-3}$. The branching fraction of its isospin partner mode $J/ψ\rightarrow\barΛπ^{-}Σ^{+}+c.c.$ is measured to be $(1.244\pm 0.002\pm0.040)\times10^{-3}$ with improved precision. Here the first uncertainties are statistical and the second ones systematic. The isospin symmetry of $Σ$ baryon in charmonium hadronic decay and the "$12\%$ rule" are tested, and no violation is found. The potential of using these channels as $Σ$ baryon sources for nuclear physics research is studied, and the momentum and angular distributions of these sources are provided.