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

Abstract

By analyzing $(448.1±2.9)×10^6$ $\psi(3686)$ 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 $\mathcal{B}_{\chi_{c0}\to 4K_S^0}$ = $(5.76±0.34±0.38)×10^{−4}$, $\mathcal{B}_{\chi_{c1}\to 4K_S^0}$ = $(0.35±0.09±0.03)×10^{−4}$ and $\mathcal{B}_{\chi_{c2}\to 4K_S^0}$ = $(1.14±0.15±0.08)×10^{−4}$, where the first uncertainties are statistical and the second are systematic, respectively.