Neutrino-excitation of baryon resonances and single pion production

Abstract

This is an attempt to describe all existing data on neutrino production of single pions in the resonance region up to W = 2 GeV in terms of the relativistic quark model of Feynman, Kislinger and Ravndal (FKR). We considered single pion production to be mediated by all interfering resonances below 2 GeV. A simple noninterfering, nonresonant background of isospin 1 2 was added. It improved agreement with experiment, particularly in the ratio of isospin amplitudes in charged current reactions, at the expense of one additional constant. All total cross sections, cross section ratios and W-distributions are well reproduced at low and high energies, with charged and neutral currents (supposing the Salam-Weinberg theory with sin 2 θ w ≈ 1 4 to be correct), and for neutrinos and antineutrinos, giving predictions where data are lacking. New predictions have been made for complex angular distributions in N π channels exhibiting strong interference between neighbouring resonances. These are sensitive (for 1.1 GeV ≲ W ≲ 1.5 GeV) to the sign of the Roper resonance P 11(1450) which is controversial in photoproduction experiments.