Differential Cross-Section

[math]-i \mathfrak{M}_{e^-e^-}=-i \left ( \frac{e^2(\mathbf p_A+\mathbf p_C)_{\mu}(\mathbf p_B+\mathbf p_D)^{\mu}}{(\mathbf p_D-\mathbf p_B)^2}- \frac{e^2(\mathbf p_A+\mathbf p_D)_{\mu}(p_B+p_C)^{\mu}}{(p_C-p_B)^2} \right )[/math]

[math] \mathfrak{M}_{e^-e^-}= e^2\left ( \frac{(\mathbf p_A \mathbf p_B+\mathbf p_C \mathbf p_D+\mathbf p_C \mathbf p_B+\mathbf p_A \mathbf p_D}{(\mathbf p_D-\mathbf p_B)^2}- \frac{(\mathbf p_A \mathbf p_B+\mathbf p_D \mathbf p_C+\mathbf p_D \mathbf p_B+\mathbf p_A \mathbf p_C}{(\mathbf p_C-\mathbf p_B)^2} \right )[/math]

[math]\mathfrak{M}_{e^-e^-}=e^2 \left (\frac{u-s}{t}+\frac{t-s}{u} \right )[/math]