Evidence of transverse polarization of $Ξ^0$ hyperon in $ψ(3686)\rightarrowΞ^0\barΞ^0$

Using $(2.712\pm0.014)\times10^{9}$ $ψ(3686)$ events collected with the BESIII detector at the BEPCII collider, we report an evidence of $Ξ^{0}$ transverse polarization with a significance of 4.4$σ$, a precise measurement of the branching fraction and the ratios between the $S$-wave and $D$-wave contributions of $ψ(3686)\toΞ^{0}\barΞ^{0}$. The weak decay parameters ($φ_{Ξ^0/\barΞ^{0}}$, $α_{Ξ^0/\barΞ^{0}}$) and the angular distribution ($α_ψ$) are also measured with higher precision compared to the previous measurements. Furthermore, two the $CP$ observables are also determined to be $A^{Ξ^0}_{CP} = -0.014 \pm 0.030 \pm 0.010$ and $Δφ^{Ξ^0}_{CP} = 0.000 \pm 0.028 \pm 0.003$~rad, which are still consistent with $CP$ conservation at 1$σ$ level under the current statistics.