Model-Independent Determination of the Spin of the ${\Omega }^{-}$ and Its Polarization Alignment in $\psi \left(3686\right)\to {\Omega }^{-}{\overline{\Omega }}^{+}$

We present an analysis of the process $\psi \left(3686\right)\to {\Omega }^{-}{\overline{\Omega }}^{+}$ (${\Omega }^{-}\to {K}^{-}\Lambda $, ${\overline{\Omega }}^{+}\to {K}^{+}\overline{\Lambda }$, $\Lambda \to p{\pi }^{-}$, $\overline{\Lambda }\to \overline{p}{\pi }^{+}$) based on a dataset of $448×{10}^{6}\text{}\text{}\psi \left(3686\right)$ decays collected with the BESIII detector at the BEPCII electron-positron collider. The helicity amplitudes for the process $\psi \left(3686\right)\to {\Omega }^{-}{\overline{\Omega }}^{+}$ and the decay parameters of the subsequent decay ${\Omega }^{-}\to {K}^{-}\Lambda $ $\left({\overline{\Omega }}^{+}\to {K}^{+}\overline{\Lambda }\right)$ are measured for the first time by a fit to the angular distribution of the complete decay chain, and the spin of the ${\Omega }^{-}$ is determined to be $3/2$ for the first time since its discovery more than 50 years ago.