Electroproduction of π+ mesons in the second and third resonance regions

Data are presented for the reaction ep → enπ+ at a nominal four-momentum transfer squared of 0.4 (GeV/c)2. The angular distribution of the π+ meson has been measured at angles up to 70° from the virtual photon direction for isobar masses in the range 1400 → 1600 MeV/c2 and, over a small angular range, close to the virtual photon direction for masses between 1600 MeV/c2 and 1860 MeV/c2. Clear evidence is seen for the presence of resonant helicity-12 amplitudes in both the second and third resonance regions. Some possible interpretations of the data are discussed.