X(1576) as Diquark-Antidiquark Bound State
  We propose that the broad $1^{--}$ resonance structure recently discovered by BES in $J/\psi\to K^{+}K^{-}\pi^{0}$ is the P-wave excitation of a diquark-antidiquark bound state. This interpretation implies that there exists a negative parity, vector nonet. A rough estimate of the mass spectrum of the nonet is presented, and the prediction for the mass of X(1576) is consistent with the experimental data. The OZI allowed strong decays are studied, it can decay into two pseudoscalars or one pseudoscalar plus one vector meson. A crucial prediction is that X(1576) should dominantly decay into $K^{+}K^{-}$, $K_{L}K_{S}$, $\phi\pi^{0}$. Since the isospin of X(1576) is $\mathbf{1}$, the observation of $I_3=1$ or $I_3=-1$ states which predominantly decays into strange mesons could provide another important test to our proposal. To search the charged $I_3=1$ isospin partner associated with X(1576) in $J/\psi\to \eta\pi^{+}\pi^{-}$, $J/\psi\to K^{+}K_{L}\pi^{-}$, $J/\psi\to K^{+}K_{S}\pi^{-}$, $J/\psi\to \phi\pi^{+}\pi^{-}$ is suggested. 
Gui-Jun Ding, Mu-Lin Yan