Observation of a broad 1^-- resonant structure around 1.5 GeV/c² in the K^+K^- mass spectrum in J/psi --> K^+K^-pi⁰

A broad peak is observed at low K^+K^- invariant mass in J/psi --> K^+K^-pi^0 decays found in a sample of 5.8\times 10^7 J/psi events collected with the BESII detector. A partial wave analysis shows that the J^PC of this structure is 1^--. Its pole position is determined to be (1576^{+49}_{-55}(stat)^{+98}_{-91}(syst)) MeV/c^2 - i(409^{+11}_{-12}$(stat)^{+32}_{-67}(syst)) MeV/c^2. These parameters are not compatible with any known meson resonances.