On the four-loop strong coupling beta-function in the SM

In the talk the leading four-loop contribution to the beta-function of the strong coupling in the SM is discussed. Some details of calculation techniques are provided. Special attention is paid to the ambiguity due to utilized $\gamma_5$ treatment and a particular prescription with anticommuting $\gamma_5$ is advocated. As a by-product of our computation the four-loop beta-function in QCD with "gluino" is also obtained.