The E2/M1 ratio in Δ photoproduction

Abstract New high-precision measurements of p( γ , π) and p( γ , γ) cross sections and beam asymmetries have been combined with other polarization ratios in a simultaneous analysis of both reactions. Compton scattering has provided two important new constraints on the photo-pion amplitude. The E2/M1 mixing ratio for the N → Δ transition extracted from this analysis is EMR = -3.0% ± 0.3 (stat + sys) ± 0.2 (model).