Automated two-loop fermion-bubble contributions at high multiplicity
We compute the gauge-invariant, helicity-summed two-loop $N_f$ contribution for $q\bar q\to n\gamma^{(*)}$, $n=2,\ldots,8$. Local ultraviolet renormalisation, infrared factorisation, analytic loop-energy integration and a new automated threshold subtraction yield finite integrals over real spatial momenta. Adaptive mul...