2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/203714We propose a measurement on the elastic $ππ$ scattering phase shift difference $δ^0_0-δ^2_0$ through $Ψ'\to J/Ψπ^+ π^-$ process in future high statistics BES-III experiment. The decay amplitude is constructed with seven Lorentz invariant form-factors and is compared with their theoretical estimation. It is found that the phase shift difference can be obtained, based on a Monte Carlo study and it is expected the phase shift in the energy region between 350 MeV to 550 MeV can be measured at future BES-III.16 pages, 1 figureHigh Energy Physics - Experimenttext