  We compute the fermionic contribution to the photon-quark form factor to
four-loop order in QCD in the planar limit in analytic form. From the divergent
part of the latter the cusp and collinear anomalous dimensions are extracted.
Results are also presented for the finite contribution. We briefly describe our
method to compute all planar master integrals at four-loop order.

High Energy Physics - Phenomenology;High Energy Physics - Theory