Pion-deuteron breakup reaction at 228 MeV

Momentum distributions of triple differential cross sections for the reaction d pn have been measured for 36 final-state pion-proton angle pairs at 228 MeV incident pion energy. The data are compared with earlier experimental results and with recent few-body calculations. In the region of quasifree elastic scattering the cross sections are typically lower than theoretical values by up to 30%. In regions away from quasifree scattering the general trends of the data are generally described, with best agreement on the low-momentum side of the distributions and with differences between theory and experiment as large as a factor of 10 in the worst cases. Together with the corresponding comparisons for the pion-deuteron elastic scattering and absorption channels, this failing might be an indication of the need to broaden the conventional calculations, or of the need to recognize an explicit quark contribution.