# Observation of $\chi_{cJ}\to4K_{S}^{0}$

## TL;DR

This paper reports the first observation of the decay modes of $oldsymbol{oldsymbol{ ext{chi}}_{cJ}}$ to four $oldsymbol{K_S^0}$ particles, measuring their branching fractions with high statistical significance using BESIII data.

## Contribution

First observation and measurement of $oldsymbol{ ext{chi}}_{cJ} o 4K_S^0$ decays, providing new data on charmonium decay channels.

## Key findings

- Branching fractions for $ ext{chi}_{c0}$, $ ext{chi}_{c1}$, and $ ext{chi}_{c2}$ decays to 4 $K_S^0$ are measured.
- Statistical significances of the observations are 26.5$\sigma$, 5.9$\sigma$, and 11.4$\sigma$ respectively.
- First experimental evidence for these decay modes.

## Abstract

By analyzing $(448.1\pm2.9)\times10^6$ $\psi(3686)$ events collected with the BESIII detector operating at the BEPCII collider, the decays of $\chi_{cJ} \to 4K_S^0$ ($J=0,1,2$) are observed for the first time with statistical significances of 26.5$\sigma$, 5.9$\sigma$ and 11.4$\sigma$, respectively. The product branching fractions of $\psi(3686)\to\gamma\chi_{cJ}$, $\chi_{cJ}\to4K_{S}^{0}$ are presented and the branching fractions of $\chi_{cJ}\to4K_{S}^{0}$ decays are determined to be $\mathcal{B}_{\chi_{c0}\to 4K_S^0}$=$(5.76\pm0.34\pm0.38)$$\times10^{-4}$, $\mathcal{B}_{\chi_{c1}\to 4K_S^0}$=$(0.35\pm0.09\pm0.03)$$\times10^{-4}$ and $\mathcal{B}_{\chi_{c2}\to 4K_S^0}$=$(1.14\pm0.15\pm0.08)$$\times10^{-4}$, where the first uncertainties are statistical and the second are systematic, respectively.