# Study of $J/\psi$ and $\psi(3686)$ decay to $\Lambda\bar{\Lambda}$ and $\Sigma^0\bar{\Sigma}^0$ final states

## TL;DR

This study measures the decay rates and angular distributions of $J/a$ and $a(3686)$ particles decaying into hyperon-antihyperon pairs, providing more precise data and first-time measurements of certain angular distributions to test theoretical decay rules.

## Contribution

The paper provides the most precise measurements of branching fractions and angular distributions for these decays, including the first measurement of $a(3686)$ decay angular distributions, advancing understanding of charmonium decays.

## Key findings

- Branching fractions agree with previous results but are more precise.
- First measurement of $a(3686)$ decay angular distributions.
- Ratios of branching fractions tested against the '12 ext{%} rule'.

## Abstract

Using $1310.6\times10^6$ $J/\psi$ and $447.9\times10^6$ $\psi(3686)$ events collected with the BESIII detector at the BEPCII $e^{+}e^{-}$ collider, the branching fractions and the angular distributions of $J/\psi$ and $\psi(3686)$ decays to $\Lambda\bar{\Lambda}$ and $\Sigma^0\bar{\Sigma}^0$ final states are measured. The branching fractions are in agreement with, and much more precise than, the averages of previously published results. The polar angular distributions of $\psi(3686)$ decays are measured for the first time, while those of $J/\psi$ decays are measured with much improved precision. In addition, the ratios of branching fractions $\frac{\mathcal{B}(\psi(3686)\to\Lambda\bar{\Lambda})}{\mathcal{B}(J/\psi\to\Lambda\bar{\Lambda})}$ and $\frac{\mathcal{B}(\psi(3686)\to\Sigma^0\bar{\Sigma}^0)}{\mathcal{B}(J/\psi\to\Sigma^0\bar{\Sigma}^0)}$ are determined to test the "12\% rule".