depend on $s, u$ and $t$ through logarithms. Under the restriction imposed by Eqs. (\[tmu\], \[umu\]) then all $A_j$ depend only on logarithms of $s, M^2, \mu^2$ in the collinear kinematics. It is convenient to represent $A_j$ in the following form: $$\label{ampl}
A_j(s, \mu^2, M^2) = A_j^{(QED)}(s, \mu^2) 
+ {A'}_j(s, \mu^2, M^2) ~,$$ where $A_j^{(QED)}(s, \mu^2)$ accounts for QED DL contributions only, i.e. the contributions of Feynman graphs without virtual $W,Z$ bosons. To calculate $A_j^{(QED)}(s, \mu^2)$ we use the cut-off $\mu$, therefore the amplitudes $A_j^{(QED)}$ do not depend on $M$. In contrast, the amplitudes ${A'}_j(s, \mu^2, M^2)$ depend on both cut-offs. These amplitudes account for DL contributions of the Feynman graphs, with one or more $W,Z$ propagators. By technical reasons, it is convenient to introduce two auxiliary amplitudes. The first one, $\tilde{A}^{(QED)}_j(s, M^2)$, is the same QED amplitude but with a cut-off $M$. The second auxiliary amplitude, $\tilde{A}_j(s, M^2)$ accounts for all electroweak DL contributions and the cut-off $M$ is used to regulate both the virtual photons and the weak bosons infrared divergences.

Beyond the Born approximation, the invariant amplitudes we have introduced depend on logarithms, the arguments of which can be chosen as in the following parameterization: $$\begin{aligned}
\label{param}
