Exclusive measurements of pi+- p --> pi+ pi+- n near threshold

The pion induced pion production reactions π±p⃗π+π±n were studied at projectile incident energies of 223, 243, 264, 284, and 305 MeV, using a cryogenic liquid hydrogen target. The Canadian High Acceptance Orbit Spectrometer was used to detect the two outgoing pions in coincidence. The experimental results are presented in the form of single differential cross sections. Total cross sections obtained by integrating the differential quantities are also reported. In addition, the invariant mass distributions from the (π+π-) channel were fitted to determine the parameters for an extended model based on that of Oset and Vicente-Vacas. We find the model parameters obtained from fitting the (π+π-) data do not describe the invariant mass distributions in the (π+π+) channel.