Observation of the $J/ψ$ and $ψ(3686)$ decays into $ηΣ^{+}\barΣ^{-}$

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