Determining the upper limit of Γee for the Y(4260)

By fitting the R values between 3.7 and 5.0 GeV measured by the BES Collaboration, the upper limit of the electron width of the newly discovered resonance Y(4260) is determined to be 580eV/c2 at 90% C.L. Together with the BaBar measurement on Γee⋅B(Y(4260)→π+π−J/ψ), this implies a large decay width of Y(4260)→π+π−J/ψ final states.