Delta(1232) contribution to real photon radiative corrections for   elastic electron-proton scattering
  Here we consider a contribution of Delta(1232) resonance to real photon radiative corrections for elastic $ep$-scattering. The effect is found to be small for past experiments to study unpolarized cross section as well as for the recent VEPP-3 experiment to investigate two-photon exchange effects by precision measurement of $e^\pm p$-scattering cross sections ratio. 
R. E. Gerasimov and V. S. Fadin
nucl-th hep-ph