We investigate the regularization-scheme dependent treatment of γ5
in the framework of dimensional regularization, mainly focusing on the
four-dimensional helicity scheme (FDH). Evaluating distinctive examples, we
find that for one-loop calculations, the recently proposed four-dimensional
formulation (FDF) of the FDH scheme constitutes a viable and efficient
alternative compared to more traditional approaches. In addition, we extend the
considerations to the two-loop level and compute the pseudo-scalar form factors
of quarks and gluons in FDH. We provide the necessary operator renormalization
and discuss at a practical level how the complexity of intermediate
calculational steps can be reduced in an efficient way.Comment: 28 pages, 7 figure
