Reaction [pi][sup +][ital p][r arrow][pi][sup +][pi][sup 0][ital p] near threshold and chiral symmetry breaking

We have measured total cross sections for the reaction [pi][sup +][ital p][r arrow][pi][sup +][pi][sup [minus]][ital p] at incident pion kinetic energies of 190, 200, 220, 240, and 260 MeV. We use this result to deduce a new value of the chiral symmetry breaking parameter, [xi]=[minus]0.25[plus minus]0.10, in a global constrained fit of the five [pi][pi][ital N] near-threshold amplitudes. Consequently, we report new soft pion model values for the [ital s]-wave [pi][pi] scattering lengths.