  Recently two-loop electroweak corrections to the neutral current four-fermion
processes at high energies have been presented. The basic ingredient of this
calculation is the evaluation of the two-loop corrections to the Abelian vector
form factor in a spontaneously broken SU(2) gauge model. Whereas the final
result and the derivation of the four-fermion cross sections from evolution
equations have been published earlier, the calculation of the form factor from
the two-loop Feynman diagrams is presented for the first time in this paper. We
describe in detail the individual contributions to the form factor and their
calculation with the help of the expansion by regions method and Mellin-Barnes
representations.
