The three loop four parton scattering in QCD

In this talk, I discuss the calculation of all helicity amplitudes
           for four-parton scattering in three-loop massless QCD. Our results
           allow us, for the first time, to verify completely the structure of
           quadrupole IR divergences at this perturbative order in QCD. From the
           high-energy limit of the amplitudes, we have extracted the three-loop
           gluon Regge trajectory in full QCD. Our findings provide a highly
           non-trivial test of the universality of high-energy factorization in QCD.