Observation of ${\eta }_c(1S)\to {\mathrm{\Sigma }}^0{\bar{\mathrm{\Sigma }}}^0$ and search for $h_c(1P)\to {\mathrm{\Sigma }}^0{\bar{\mathrm{\Sigma }}}^0$ via $\psi (3686)$ transitions

Using $(2712.4\pm 14.3)\times {10}^6\psi (3686)$ events collected by the BESIII detector operating at the BEPCII collider, the hadronic decay ${\eta }_c\to {\mathrm{\Sigma }}^0\overline{{\mathrm{\Sigma }}^0}$ is observed for the first time via the radiative transition from $\psi (3686)$. It is found that the branching fraction has a significant dependence on the interference pattern between ${\eta }_c(1S)$ and non-${\eta }_c(1S)$ processes. They are determined to be ${\displaystyle \mathcal{B}({\eta }_c(1S)\to {\mathrm{\Sigma }}^0\overline{{\mathrm{\Sigma }}^0})=(2.59\pm 0.14(stat)\pm 0.44(syst))\times {10}^{-3}}$ and $(1.18\pm 0.12(stat)\pm 0.21(syst))\times {10}^{-3}$, for the destructive and constructive interference scenarios, respectively. No significant signal is observed for the decay $h_c\to {\mathrm{\Sigma }}^0\overline{{\mathrm{\Sigma }}^0}$ in the hadronic transition $\psi (3686)\to {\pi }^0{h}_c$, and an upper limit on its branching fraction is set to be $1.02\times {10}^{-4}$ at the 90% confidence level.