The Renormalization Group
The relation between the subtracted Green’s functions with different choices of subtraction point in the \(\phi ^4_4\) model. The running coupling constant. Functional equations of the renormalization group. Differential renormalization group equations of the Gell-Mann–Low and the Callan–Symanzik type. The \(\beta \) function. Reliability of the perturbative approximations. The phenomenon of dimensional transmutation in renormalized quantum field theory.