Observation ofχcJ→4KS0

By analyzing $(448.1\ifmmode\pm\else\textpm\fi{}2.9)\ifmmode\times\else\texttimes\fi{}1{0}^{6}$ $\ensuremath{\psi}(3686)$ events collected with the BESIII detector operating at the BEPCII collider, the decays of ${\ensuremath{\chi}}_{cJ}\ensuremath{\rightarrow}4{K}_{S}^{0}$ ($J=0$, 1, 2) are observed for the first time with statistical significances of $26.5\ensuremath{\sigma}$, $5.9\ensuremath{\sigma}$ and $11.4\ensuremath{\sigma}$, respectively. The product branching fractions of $\ensuremath{\psi}(3686)\ensuremath{\rightarrow}\ensuremath{\gamma}{\ensuremath{\chi}}_{cJ}$, ${\ensuremath{\chi}}_{cJ}\ensuremath{\rightarrow}4{K}_{S}^{0}$ are presented, and the branching fractions of ${\ensuremath{\chi}}_{cJ}\ensuremath{\rightarrow}4{K}_{S}^{0}$ decays are determined to be ${\mathcal{B}}_{{\ensuremath{\chi}}_{c0}\ensuremath{\rightarrow}4{K}_{S}^{0}}=(5.76\ifmmode\pm\else\textpm\fi{}0.34\ifmmode\pm\else\textpm\fi{}0.38)\ifmmode\times\else\texttimes\fi{}1{0}^{\ensuremath{-}4}$, ${\mathcal{B}}_{{\ensuremath{\chi}}_{c1}\ensuremath{\rightarrow}4{K}_{S}^{0}}=(0.35\ifmmode\pm\else\textpm\fi{}0.09\ifmmode\pm\else\textpm\fi{}0.03)\ifmmode\times\else\texttimes\fi{}1{0}^{\ensuremath{-}4}$ and ${\mathcal{B}}_{{\ensuremath{\chi}}_{c2}\ensuremath{\rightarrow}4{K}_{S}^{0}}=(1.14\ifmmode\pm\else\textpm\fi{}0.15\ifmmode\pm\else\textpm\fi{}0.08)\ifmmode\times\else\texttimes\fi{}1{0}^{\ensuremath{-}4}$, where the first uncertainties are statistical and the second are systematic, respectively.