X(1576) as diquark-antidiquark bound state

We propose that the broad 1−− resonance structure recently discovered by BES in J/ψ→K+K−π0 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−, KLKS, ϕπ0. The observation of I3=1 or I3=−1 states which predominantly decays into strange mesons could provide another important test to our proposal. To search the charged I3=1 isospin partner of X(1576), careful search in J/ψ→K+KLπ−, J/ψ→K+KSπ− and J/ψ→ϕπ+π− is suggested.