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

Based on 58 million BESII J / ψ events, the K ¯ ∗ ( 892 ) 0 K + 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 +64 MeV / c 2 and 499 ± 52 −87 +55 MeV / c 2 , respectively, corresponding to a pole at ( 841 ± 30 −73 +81 ) − i ( 309 ± 45 −72 +48 ) MeV / c 2 .