ππ scattering amplitudes within the sub-threshold triangle

The on-shell ππ scattering amplitudes within and on the boundary of the subthreshold triangle (0 ≤ s ≤ Σ, 0 ≤ t ≤ Σ, 0 ≤ u ≤ Σ ≡ 4μ²) are investigated. Interior Dispersion Relations, when combined with experimental ππ phase shifts, inelasticities, and scattering lengths, provide an almost perfect tool for this study. The general results obtained are in striking agreement with the chiral model of Weinberg.