2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/121317Three 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)-> DD_1(2420), D_1->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.6 pages, 3 figuresHigh Energy Physics - Experimenttext