The (6550), (6900), (7280) Resonances as the , States

Within the diquark–antidiquark model the masses of the 0 , resonances are calculated, using the expansion of the four-quark wave function in the set of the hyperspherical functions. The interaction is defined via a universal pairwise potential, which does not contain fitting parameters. The resulting masses are shown to be very sensitive to the value of -quark mass, chosen in relativistic string Hamiltonian, and , 1.30, 1.43 (in GeV) are considered. The choice of , equal to the current mass, GeV, yields three ( , 1, 2) states in a very good agreement with the masses of the (6550), (6900), (7280) resonances, if the gluon-exchange interaction is totally neglected. This fact indicates possible screening of the gluon-exchange interaction in the system. For GeV the ground state mass MeV is obtained in agreement with experiment only if is used, however, in this case the masses of the 2 , 3 radial excitations exceed the masses of (6900), (7280) by 100 MeV.