Incoherent pion production in neutrino-deuteron interactions

Within the multiple scattering formulation, the incoherent pion production in neutrino-deuteron reactions at energies near the Delta(1232) resonance is investigated. The calculations include an impulse term and one-loop contributions from nucleon-nucleon (NN) and pion-nucleon (pi N) final-state interactions. The input amplitudes of pi N scattering and electroweak pion-production reaction on the nucleon are generated from a dynamical model, which describes very extensive data of pi N scattering and both the electromagnetic and the weak pion-production reactions on the nucleon. The NN scattering amplitudes are generated from the Bonn potential. The validity of the calculational procedures is established by giving a reasonably good description of the data of pion photoproduction on the deuteron. The constructed model is then applied to predict the cross sections of nu + d -> mu(-) + pi(+) + n + p and nu + d -> mu(-) + pi(0) + p + p reactions. The importance of including the NN final-state interactions to understand the experimental data of these neutrino-deuteron reactions is demonstrated. Our results strongly suggest that the spectator approximation used in the previous analyses to extract the pion-production cross sections on the nucleon from the data on the deuteron is not valid for the nu + d -> mu(-) + pi(+) + n + p, but is a good approximation for nu + d -> mu(-) + pi(0) + p + p.