Observation of the decay $ψ(3686) \to Σ^-\barΣ^+$ and measurement of its angular distribution

Abstract

Using $(448.1\pm2.9)\times10^6$ $ ψ(3686)$ events collected with the BESIII detector at the BEPCII collider, the decay $ψ(3686)\toΣ^-\barΣ^+$ is observed for the first time with a branching fraction of $(2.82\pm0.04_{\rm stat.}\pm0.08_{\rm syst.})\times10^{-4}$, and the angular parameter $α_{ Σ^-}$ is measured to be $0.96\pm0.09_{\rm stat.} \pm 0.03_{\rm syst.}$.