Search for Y(4260) in B→ Y(4260 ) K decay mode at belle.

Abstract

Y(4260) is an exotic charmonium-like state with 4230±8 MeV/c2 mass and 55±19 MeV width. The Y(4260)′s decay to J/ψππ suggests, it to be a charmonium (cc¯) meson. But its mass is not consistent with any of 1−− cc¯ state. Several models have been proposed to explain the nature of Y(4260) including cc¯g hybrid model, tetraquark, D1D, D0D∗ molecule, J/ψf0(980) molecule, and so on. This state is so interesting that a charged state Zc(3900) is observed in its decay mode and Zc(3900) is a tetraquark state. Some recent studies suggest Y(4260) be an admixture of tetraquark and charmonium state. It has been suggested that the structure of Y(4260) can be estimated if one measured branching fraction of B→Y(4260)K. Till now, this state has been only produced by ISR or e+e− annihilation. We search for B→Y(4260)K, where Y(4260)→J/ψππ decay mode using the full Υ(4S) data collected by the Belle detector at the asymmetric KEKB e+e− collider.