Paper detail

Observation of $η_{c}$ decay into $Σ^{+}\barΣ^{-}$ and $Ξ^{-}\barΞ^{+}$ final states

Using a data sample of $2.25\times10^{8}$ $J/ψ$ events collected with the BESIII detector, we present the first observation of the decays of $η_{c}$ mesons to $Σ^{+}\barΣ^{-}$ and $Ξ^{-}\barΞ^{+}$. The branching fractions are measured to be $(2.11\pm0.28_{\rm stat.}\pm0.18_{\rm syst.}\pm0.50_{\rm PDG})\times10^{-3}$ and $(0.89\pm0.16_{\rm stat.}\pm0.08_{\rm syst.}\pm0.21_{\rm PDG})\times10^{-3}$ for $η_{c} \to Σ^{+}\barΣ^{-}$ and $Ξ^{-}\barΞ^{+}$, respectively. These branching fractions provide important information on the helicity selection rule in charmonium-decay processes.