Observation of the decay ${\chi }_{cJ}\to {\Omega }^{-}{\overline{\Omega }}^{+}$

Using an ${e}^{+}{e}^{-}$ collision data sample of $\left(27.08±0.14\right)×{10}^{8}\text{}\text{}\psi \left(3686\right)$ events collected by the BESIII detector, we report the first observation of ${\chi }_{cJ}\to {\Omega }^{-}{\overline{\Omega }}^{+}$ ($J=0$, 1, 2) decays with significances of $5.6\sigma $, $6.4\sigma $, and $18\sigma $, respectively, where the ${\chi }_{cJ}$ mesons are produced in the radiative $\psi \left(3686\right)$ decays. The branching fractions are determined to be $B\left({\chi }_{c0}\to {\Omega }^{-}{\overline{\Omega }}^{+}\right)=\left(3.51±0.54±0.29\right)×{10}^{-5}$, $B\left({\chi }_{c1}\to {\Omega }^{-}{\overline{\Omega }}^{+}\right)=\phantom{\rule{0ex}{0ex}}\left(1.49±0.23±0.10\right)×{10}^{-5}$, and $B\left({\chi }_{c2}\to {\Omega }^{-}{\overline{\Omega }}^{+}\right)=\left(4.52±0.24±0.18\right)×{10}^{-5}$, where the first and second uncertainties are statistical and systematic, respectively.