QED vertex form factors at two loops Original Research Article

We present the closed analytic expression of the form factors of the two-loop QED vertex amplitude for on-shell electrons of finite mass m and arbitrary momentum transfer S=−Q2. The calculation is carried out within the continuous D-dimensional regularization scheme, with a single continuous parameter D, the dimension of the space–time, which regularizes at the same time ultraviolet (UV) and infrared (IR) divergences. The results are expressed in terms of 1-dimensional harmonic polylogarithms of maximum weight 4.