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 is very difficult to accommodate Y(4260) as a conventional cc radial excitation or a D-wave state. It cannot be a hadronic molecule. Its production mechanism and special decay pattern do 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, 1, = 0 component of the virtual photon should have produced its isovector partner Y'(4260), which may be searched for in the decay channel pi (+)pi -pi(0)J/psi 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 DD, D* D very easily. Its not-so-large width and the non-observation of DD mode tend 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. (c) 2005 Elsevier B.V. All rights reserved.