Compton-effect tensor with a heavy photon

The contribution of one-loop corrections to the square of the matrix element for the process e+γ*→e+γ summed over the polarizations of all the particles except the heavy photon γ* is obtained for the case where the photon virtual momentum and the momentum transfer between the electrons are large compared to the electron mass. All the terms whose contribution to the cross section does not vanish when the electron mass tends to zero are kept