Hyperon Physics at BESIII

Abstract

The BESIII detector on the BEPCII collider collected the world's largest dataset at the peaks of $J/\psi$, $\psi (3686)$ and $\psi (3770)$. The use of polarization and entanglement states in multidimensional angular distribution analysis can provide new probes to the production and decay characteristics of hyperon anti hyperon pairs. In a recent series of studies, significant transverse polarization in hyperon decay has been observed in $J/\psi$, $\psi (3686)$ decaying into the $\Lambda \bar{\Lambda }$, ${\Sigma }^{+}{\bar{\Sigma }}^{-}$, ${\Xi }^0{\bar{\Xi }}^0$ and ${\Xi }^{-}{\bar{\Xi }}^{+}$ final states. The weak decay parameters of hyperons and antihyperons are also independently determined for the first time. The most accurate testing for direct $CP$ violation has been achieved based on the measured weak decay parameters.

Comments: Proceedings of the 21st Lomonosov Conference on Elementary Particle Physics, Aug. 24-30, 2023. 4 pages, 3 figures, 3 tables