Study of ?cJ decaying into K? (892) K ¯

Abstract

Using a data sample of 106 million ?(3686) events collected with the BESIII detector operated at the BEPCII storage ring, we study for the first time the decays ?cJ??KS0K±?? and ?cJ??K+K-?0 in the E1 radiative transition ?(3686)???cJ. The decays are dominated by the three-body decay ?cJ?K?(892)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 KK¯? invariant mass distribution, a structure near the K?(892)K¯ mass threshold is observed, and the corresponding mass and width are measured to be 1412±4(stat)±8(sys)MeV/c2 and ?=84±12(stat)±40(sys)MeV, respectively. The observed state favors an assignment to the h1(1380), considering its possible JPC and comparing its mass, width and decay mode to those reported in the Particle Data Group. © 2015 American Physical Society.