Radiative Corrections to the Lepton Current in Unpolarized Elastic Lp-Interaction for Fixed Q^2 and Scattering Angle

The kinematical difference between the description of radiative effects for fixed Q^2 vs a fixed scattering angle in the elastic lepton-proton (lp)-scattering is discussed. The technique of calculation as well as explicit expressions for radiative corrections to the lepton current in unpolarized elastic lp-scattering for these two cases are presented without using an ultrarelativistic approximation. A comparative numerical analysis within kinematic conditions of Jefferson Lab measurements and MUSE experiment in PSI is performed.