Search for hadronic transition $\chi_{cJ}\to\eta_{c}\pi^{+}\pi^{-}$ and observation of $\chi_{cJ}\to K\bar{K}\pi\pi\pi$

Abstract

Hadronic transitions of $\chi_{cJ}\to \eta_{c}\pi^{+}\pi^{-}$ (J=0, 1, 2) are
searched for using a sample of $1.06\times 10^{8}$ $\psi(3686)$ 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 $\phi\pi^{+}\pi^{-}\pi^{0}$ (J=0, 1, 2) are measured
for the first time.