Observation of the $J/\psi $ and $\psi \left(3686\right)$ decays into $\eta {\Sigma }^{+}{\overline{\Sigma }}^{-}$

The decays $J/\psi \to \eta {\Sigma }^{+}{\overline{\Sigma }}^{-}$ and $\psi \left(3686\right)\to \eta {\Sigma }^{+}{\overline{\Sigma }}^{-}$ are observed for the first time, using $\left(10087±44\right)×{10}^{6}\text{}\text{}J/\psi $ and $\left(448.1±2.9\right)×{10}^{6}\text{}\text{}\psi \left(3686\right)$ events collected with the BESIII detector at the BEPCII collider. We determine the branching fractions of these two decays to be $B\left(J/\psi \to \eta {\Sigma }^{+}{\overline{\Sigma }}^{-}\right)=\left(6.34±0.21±0.37\right)×{10}^{-5}$ and $B\left(\psi \left(3686\right)\to \eta {\Sigma }^{+}{\overline{\Sigma }}^{-}\right)=\left(9.59±2.37±0.61\right)×{10}^{-6}$, where the first uncertainties are statistical and the second are systematic. The ratio of these two branching fractions is determined to be $\frac{B\left(\psi \left(3686\right)\to \eta {\Sigma }^{+}{\overline{\Sigma }}^{-}\right)}{B\left(J/\psi \to \eta {\Sigma }^{+}{\overline{\Sigma }}^{-}\right)}=\left(15.1±3.8\right)%$, which is in agreement with the "12% rule."