Search for hadronic transition $chi_{cJ}toeta_{c}pi^{+}pi^{-}$ and observation of $chi_{cJ}to Kbar{K}pipipi$

Hadronic transitions of $chi_{cJ}to eta_{c}pi^{+}pi^{-}$ (J=0, 1, 2) are searched for using a sample of $1.06times 10^{8}$ $psi(3686)$ events collected with the BESIII detector at the BEPCII storage ring. The $etac$ is reconstructed with $K_{S}^{0}K^{+}pi^{-}+c.c.$ and $K^{+}K^{-}pi^{0}$ final states. No signals are observed in any of the three $chi_{cJ}$ states in either $etac$ decay mode. At the 90% confidence level, the upper limits are determined to be $BR(chi_{c0}to eta_{c}pi^{+}pi^{-})<0.07%$, $BR(chi_{c1}to eta_{c}pi^{+}pi^{-})<0.32%$, and $BR(chi_{c2}to eta_{c}pi^{+}pi^{-})<0.54%$. The upper limit of $BR(chi_{c1}to eta_{c}pi^{+}pi^{-}$ is lower than the existing theoretical prediction by almost an order of magnitude. The branching fractions of $chi_{cJ}to K_{S}^{0}K^{+}pi^{-}pi^{+}pi^{-}+c.c.$, $K^{+}K^{-}pi^{+}pi^{-}pi^{0}$, $omega K^{+}K^{-}$ and $phipi^{+}pi^{-}pi^{0}$ (J=0, 1, 2) are measured for the first time.