QED RADIATIVE-CORRECTIONS FOR PARTON DISTRIBUTIONS

I discuss radiative corrections due to the emission of photons from quarks which contribute to deep inelastic lepton-nucleon scattering as well as to pp collisions at high energies. These corrections are dominated by quark-mass singularities which have to be absorbed into the parton distribution functions. Observable effects appear as a modification of the Q(2) dependence of the distribution functions. Numerical results indicate, however, that these QED corrections are negligible except at extremely large Q(2) and large x. Therefore it is safe to neglect the single and multiple photon effects in pp scattering at CERN LHC energies.