Four-loop beta function in N=2 supersymmetric Yang-Mills theory, dimensional reduction, and treatment of $γ_5$

Adopting the dimensional-reduction scheme, we diagrammatically compute, at four loops, the beta function of N=2 supersymmetric Yang-Mills theory, which is well known to vanish beyond one loop. This provides a formidable testbed for both the treatment of the problematic $γ_5$ Dirac matrix in D dimens