The two-loop helicity amplitudes for $q \bar q' \to V_1 V_2 \to 4~\mathrm{leptons}$

Understand

We compute the two-loop massless QCD corrections to the helicity amplitudes for the production of two massive vector bosons in quark-antiquark annihilation, allowing for an arbitrary virtuality of the vector bosons: $q \bar q' \to V_1V_2$.

• Combining with the leptonic decay currents, we obtain the full two-loop QCD description of the corresponding electroweak four-lepton production processes.
• The calculation is performed by projecting the two-loop diagrams onto an appropriate basis of Lorentz structures.
• All two-loop Feynman integrals are reduced to a basis of master integrals, which are then computed using the differential equations method and optimised for numerical performance.