Isobar excitation in proton-proton bremsstrahlung

Abstract The contribution of intermediate nucleon isobars to proton-proton bremsstrahlung is calculated in a relativistic model. Using conventional coupling constants and form factors for the exchange of π - and ρ-mesons we find that for photon energies ω > 100 MeV isobar excitation increases the cross section markedly over the prediction of soft-photon calculations. Our results agree well with recent experiments at incident proton energy T lab =730 MeV.