ar X iv : h ep - p h / 05 07 02 5 v 1 2 J ul 2 00 5 The Possible Interpretations of Y ( 4260 )

The recently observed Y(4260) lies far above the decay threshold with a width less than 100 MeV. We argue that it’s very difficult to accommodate Y(4260) as a conventional cc̄ radial excitation or a D-wave state. It can’t be a hadronic molecule. Its special decay pattern does not favor the glueball interpretation. If Y(4260) is a scalar tetraquark, it must be produced by the I = 0 component of the virtual photon. Then the I = 1, Iz = 0 component of the virtual photon should have produced its isovector partner Y ′(4260), which may be searched for in the decay channel π+π−π0J/ψ using exactly the same database from the initial state radiation process. The observation/non-observation of Y ′(4260) can easily confirm/reject the tetraquark hypothesis. However, a tetraquark far above threshold can fall apart into DD̄,D∗D̄ very easily. Its not-so-large width and the non-observation of DD̄ mode tends to disfavor the tetraquark hypothesis. Hence the only feasible interpretation is a hybrid charmonium if Y(4260) is NOT an experimental artifact. At present, none of the experimental information from BABAR measurement is in conflict with the hybrid charmonium picture. PACS number: 12.39.-x, 13.20.Gd, 13.25.Gv, 14.40.Gx