Determination of the pi(+/-)p -> pi(+/-)pi(+)n cross section near threshold - art. no. 025201

The total cross section for the pi(-) p --> pi(-) pi(+) n reaction has been measured at incident pion kinetic energies of 200, 190, 184, 180, and 176 MeV, and cross sections for the pi(+) p --> pi(+) pi(+) n reaction were obt ained at 200 and 184 MeV. A fit of these cross sections by heavy baryon chi ral perturbation theory yields values of 8.5 +/- 0.6(m(pi)(-3)) and 2.5+/-0 .1(m(pi)(-3)) for the reaction matrix elements A(10) and A(32), and, for th e s-wave isospin-0 and isospin-2 pi-pi scattering lengths, the values a(0) = 0.23+/-0.08(m(pi)(-1)) and a(2) = -0.031+/-0.008(m(pi)(-1)), respectively .