Observation of the decay $\psi(3686) \to \Sigma^-\bar\Sigma^+$ and measurement of its angular distribution

TL;DR

This paper reports the first observation of the decay $ ext{psi}(3686) o ext{Sigma}^- ar{ ext{Sigma}}^+$ using a large data sample, measuring its branching fraction and angular distribution parameter with high precision.

Contribution

The study provides the first measurement of the decay's branching fraction and angular distribution, offering new insights into charmonium decay dynamics.

Findings

Branching fraction of $(2.82 extpm0.04 extpm0.08) imes10^{-4}$

Angular parameter $ ext{alpha}_{ ext{Sigma}^-} = 0.96 extpm0.09 extpm0.03$

First observation of this decay mode

Abstract

Using $(448.1\pm2.9)\times10^6$ $ \psi(3686)$ events collected with the BESIII detector at the BEPCII collider, the decay $\psi(3686)\to\Sigma^-\bar\Sigma^+$ is observed for the first time with a branching fraction of $(2.82\pm0.04_{\rm stat.}\pm0.08_{\rm syst.})\times10^{-4}$, and the angular parameter $\alpha_{ \Sigma^-}$ is measured to be $0.96\pm0.09_{\rm stat.} \pm 0.03_{\rm syst.}$.