Quark and gluon form factors to four loop order in QCD: the $N_f^3$ contributions

Understand

We calculate the four-loop massless QCD corrections with three closed quark lines to quark and gluon form factors.

• We apply a novel integration by parts algorithm based on modular arithmetic and compute all relevant master integrals for arbitrary values of the space-time dimension.
• This is the first calculation of a gluon form factor at this perturbative order in QCD.