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.