Numerical study of radiative corrections in the low $Q^2$ region at HERA
  A detailed numerical study of radiative corrections in the low $Q^2$ region at the HERA $ep$ collider was performed. The specific case of the total photoproduction cross section measurement was taken as an example. Two different programs, TERAD91 and HERACLES4.2, were used to get an estimation of the size of radiative effects. It was found that radiative corrections can be quite large in some points of the space of leptonic $(x,y)$ variables. However, after imposing experimentally feasible cuts on the radiated photon and the hadronic final state one gets corrections at the level of a few per cent. 
K.Charchula and J.Gajewski