M4 transitions observed in pion inelastic scattering on 15N.

Cross sections for ${\ensuremath{\pi}}^{+}$ and ${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$ elastic and inelastic scattering to states in $^{15}\mathrm{N}$ have been measured at an incident pion energy of 164 MeV. Transitions to states at 10.7, 12.5, 14.0, and 17.2 MeV were found to contain significant M4 strength. The M4 assignments are supported both by angular distribution shapes and by additional ${\ensuremath{\pi}}^{+}$ cross sections measured at 120 and 260 MeV. The angular distributions are compared with distorted-wave impulse-approximation calculations to extract isoscalar and isovector spectroscopic amplitudes. These amplitudes are compared with model predictions.