Study of $χ_{cJ}$ decaying into $ϕ$ $K^*(892)$ $\bar{K}$

Abstract

Using a data sample of 106 million $ψ(3686)$ events collected with the BESIII detector operated at the BEPCII storage ring, we study for the first time the decay $χ_{cJ}\toϕK^{0}_S K^{\pm}π^{\mp}$ and $χ_{cJ}\toϕK^{+} K^{-}π^{0}$ in the E1 radiative transition $ψ(3686)\toγχ_{cJ}$. The decays are dominated by the three-body decay $χ_{cJ}\to ϕK^*(892)\bar{K}$. We measure branching fractions for this reaction via the neutral and charged $K^*(892)$ and find them consistent with each other within the expectation of isospin symmetry. In the $K\bar{K}π$ invariant mass distribution a structure near the $K^*(892)\bar{K}$ mass threshold is observed, and the corresponding mass and width are measured to be $1412\pm4(\mathrm{stat.})\pm8(\mathrm{sys.}) \mathrm{MeV}/c^2$ and $Γ$ = $84\pm12(\mathrm{stat.})\pm40(\mathrm{sys.}) \mathrm{MeV}$, respectively. The observed state favors an assignment to the $h_1(1380)$, considering its possible $J^{PC}$ and comparing its mass, width and decay mode to those reported in the Particle Data Group.

17 pages, 24 figures