Mixed EW-QCD two-loop amplitudes for $qbar{q} to ell^+ell^-$ and $gamma_5$ scheme independence of multi-loop corrections

We perform a dedicated study of the $q bar{q}$-initiated two-loop electroweak-QCD Drell-Yan scattering amplitude in dimensional regularization schemes for vanishing light quark and lepton masses. For the relative order $alpha$ and $alpha_s$ one-loop Standard Model corrections, details of our comparison to the original literature are given. The infrared pole terms of the mixed two-loop amplitude are governed by a known generalization of the dipole formula and we show explicitly that exactly the same two-loop polarized hard scattering functions are obtained in both the standard t Hooft-Veltman-Breitenlohner-Maison $gamma_5$ scheme and Kreimers anticommuting $gamma_5$ scheme.