Evidence for κ meson production in J/ψ→K¯∗(892)0K+π− process

Based on 58 million BESII J/ψ events, the K¯∗(892)0K+π− channel in K+K−π+π− is studied. A clear low mass enhancement in the invariant mass spectrum of K+π− is observed. The low mass enhancement does not come from background of other J/ψ decay channels, nor from phase space. Two independent partial wave analyses have been performed. Both analyses favor that the low mass enhancement is the κ, an iso-spinor scalar resonant state. The average mass and width of the κ in the two analyses are 878±23−55+64MeV/c2 and 499±52−87+55MeV/c2, respectively, corresponding to a pole at (841±30−73+81)−i(309±45−72+48)MeV/c2.