Two-loop helicity amplitudes for diphoton production with massive quark loop

A bstract We compute two-loop helicity amplitudes in QCD for diphoton production through quark- and gluon-initiated channels, accounting for a massive internal quark loop by keeping its full mass dependence. Using physical projectors, we directly decompose the amplitude into its helicity components. By renormalising the heavy quark mass in on-shell, and other quantities in $$\overline{\text{MS} }$$ schemes, we obtain finite remainders. We provide benchmark values of the helicity amplitudes, expressed in terms of a canonical basis for all the non-elliptic integrals. We also present our findings through plots. The effect of a heavy quark is expected to play a crucial role in high-luminosity LHC.