DETERMINATION OF LOW ENERGY PION-PION SCATTERING

The dispersion relation for forward π±π0 elastic scattering is solved by imposing consistency in the low-energy region between input cross section and output cross section. The I = 2, S-partial wave amplitude has a scattering length a2 ap; 0.26 and vanishes at ω ap; 457 MeV. The model proposed by Wanders and collaborators is used to test this behavior: no serious incompatibility with the conditions of Martin is found if the I = 0. S-partial wave amplitude has a scattering length a0 ap; 0.8 and vanishes at s ap; -2.4. © 1969.