Measurements of the absolute branching fractions of ${\Omega }^{-}$ decays and test of the $\Delta I=1/2$ rule

Based on a dataset of $\left(27.12±0.10\right)×{10}^{8}$ $\psi \left(3686\right)$ events collected at the BESIII experiment, the absolute branching fractions of the three dominant ${\Omega }^{-}$ decays are measured to be ${B}_{{\Omega }^{-}\to {\Xi }^{0}{\pi }^{-}}=\phantom{\rule{0ex}{0ex}}\left(25.03±0.44±0.53\right)%$, ${B}_{{\Omega }^{-}\to {\Xi }^{-}{\pi }^{0}}=\left(8.43±0.52±0.28\right)%$, and ${B}_{{\Omega }^{-}\to \Lambda {K}^{-}}=\left(66.3±0.8±2.0\right)%$, where the first and second uncertainties are statistical and systematic, respectively. The ratio between ${B}_{{\Omega }^{-}\to {\Xi }^{0}{\pi }^{-}}$ and ${B}_{{\Omega }^{-}\to {\Xi }^{-}{\pi }^{0}}$ is determined to be $2.97±0.19±0.11$, which is in good agreement with the PDG value of $2.74±0.15$, but greater by more than four standard deviations than the theoretical prediction of 2 obtained from the $\Delta I=1/2$ rule.