Evidence of transverse polarization of $\hat{I}{ž}^0$ hyperon in $\ddot{I}ˆ(3686)\to \hat{I}{ž}^0\bar{\hat{I}}{ž}^0$

Abstract

Using $(2.712\pm 0.014)\times 10^9$ $\ddot{I}ˆ(3686)$ events collected with the BESIII detector at the BEPCII collider, we report an evidence of $\hat{I}{ž}^0$ transverse polarization with a significance of 4.4$\ddot{I}ƒ$, a precise measurement of the branching fraction and the ratios between the $S$-wave and $D$-wave contributions of $\ddot{I}ˆ(3686)\to \hat{I}{ž}^0\bar{\hat{I}}{ž}^0$. The weak decay parameters ($\ddot{I}{•}_{\hat{I}{ž}^0/\bar{\hat{I}}{ž}^0}$, $\hat{I}{\pm }_{\hat{I}{ž}^0/\bar{\hat{I}}{ž}^0}$) and the angular distribution ($\hat{I}{\pm }_{\ddot{I}}ˆ$) are also measured with higher precision compared to the previous measurements. Furthermore, two the $CP$ observables are also determined to be $A_{CP}^{\hat{I}{ž}^0}=-0.014\pm 0.030\pm 0.010$ and $\hat{I}”\ddot{I}{•}_{CP}^{\hat{I}{ž}^0}=0.000\pm 0.028\pm 0.003$~rad, which are still consistent with $CP$ conservation at 1$\ddot{I}ƒ$ level under the current statistics.

10 pages, 3 figures, 3 tables, consistent with the publication in Phys. Rev. D (Letter) 113, L091501 (2026)