Observation of ${\chi }_{cJ}\to p\overline{p}{K}_{S}^{0}{K}^{-}{\pi }^{+}+c.c.$

By analyzing $\left(27.12±0.14\right)×{10}^{8}$ $\psi \left(3686\right)$ events collected with the BESIII detector operating at the BEPCII collider, the decays ${\chi }_{cJ}\to p\overline{p}{K}_{S}^{0}{K}^{-}{\pi }^{+}+c.c.$ $\left(J=0,1,2\right)$ are observed for the first time with statistical significances greater than $10\sigma $. The branching fractions of these decays are determined to be $B\left({\chi }_{c0}\to p\overline{p}{K}_{S}^{0}{K}^{-}{\pi }^{+}+c.c.\right)=\left(2.61±0.27±0.32\right)×{10}^{-5}$, $B\left({\chi }_{c1}\to p\overline{p}{K}_{S}^{0}{K}^{-}{\pi }^{+}+c.c.\right)=\phantom{\rule{0ex}{0ex}}\left(4.16±0.24±0.46\right)×{10}^{-5}$, and $B\left({\chi }_{c2}\to p\overline{p}{K}_{S}^{0}{K}^{-}{\pi }^{+}+c.c.\right)=\left(5.63±0.28±0.46\right)×{10}^{-5}$, respectively. The processes ${\chi }_{c1,2}\to \overline{p}\Lambda \left(1520\right){K}_{S}^{0}{\pi }^{+}+c.c.$ are also observed, with statistical significances of $5.7\sigma $ and $7.0\sigma $, respectively. Evidence for ${\chi }_{c0}\to \overline{p}\Lambda \left(1520\right){K}_{S}^{0}{\pi }^{+}+c.c.$ is found with statistical significances of $3.3\sigma $. The corresponding branching fractions are determined to be $B\left({\chi }_{c0}\to \phantom{\rule{0ex}{0ex}}\overline{p}\Lambda \left(1520\right){K}_{S}^{0}{\pi }^{+}+c.c.\right)=\left(1.6{1}_{-0.64}^{+0.68}±0.23\right)×{10}^{-5}$, $B\left({\chi }_{c1}\to \overline{p}\Lambda \left(1520\right){K}_{S}^{0}{\pi }^{+}+c.c.\right)=\left({4.06}_{-0.76}^{+0.80}±\phantom{\rule{0ex}{0ex}}0.52\right)×{10}^{-5}$, and $B\left({\chi }_{c2}\to \overline{p}\Lambda \left(1520\right){K}_{S}^{0}{\pi }^{+}+c.c.\right)=\left(4.0{9}_{-0.84}^{+0.87}±0.42\right)×{10}^{-5}$. Here, the first uncertainties are statistical and the second ones are systematic.