The pi-pi mass spectrum in Y(4260) -> pi-pi-J/psi
Abstract
Three ways of fitting the pi-pi mass spectrum in Y(4260) decays are studied. Data presented recently by Belle cannot be fitted by the pi-pi S-wave intensity for elastic scattering. They can be fitted by adding a rather arbitrary destructive interference with the sigma pole term. A better fit may be obtained with the decay sequence Y -> pi-H, H -> pi-J/psi, where H is a JPC=1-- c-cbar-q-qbar state peaking at 4.0 GeV with a width ~280 MeV. A third possibility, involving a triangle diagram due to Y(4260)-> DD1(2420), D1->D*(2007)-pi, DD*->pi-J/psi fails to fit the data. The first and second possibilities could be resolved by analysis of the Y(4260) Dalitz plot and pi-J/psi mass projection, not presently publicly available.
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