Observation of ${\chi }_{cJ}\to 4{K}_{S}^{0}$

By analyzing $\left(448.1±2.9\right)×1{0}^{6}$ $\psi \left(3686\right)$ events collected with the BESIII detector operating at the BEPCII collider, the decays of ${\chi }_{cJ}\to 4{K}_{S}^{0}$ ($J=0$, 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 $\psi \left(3686\right)\to \gamma {\chi }_{cJ}$, ${\chi }_{cJ}\to 4{K}_{S}^{0}$ are presented, and the branching fractions of ${\chi }_{cJ}\to 4{K}_{S}^{0}$ decays are determined to be ${B}_{{\chi }_{c0}\to 4{K}_{S}^{0}}=\left(5.76±0.34±0.38\right)×1{0}^{-4}$, ${B}_{{\chi }_{c1}\to 4{K}_{S}^{0}}=\left(0.35±0.09±0.03\right)×1{0}^{-4}$ and ${B}_{{\chi }_{c2}\to 4{K}_{S}^{0}}=\left(1.14±0.15±0.08\right)×1{0}^{-4}$, where the first uncertainties are statistical and the second are systematic, respectively.