Banks–Zaks fixed point

In quantum chromodynamics (and also N = 1 super quantum chromodynamics) with massless flavors, if the number of flavors, N_f, is sufficiently small (i.e. small enough to guarantee asymptotic freedom, depending on the number of colors), the theory can flow to an interacting conformal fixed point of the renormalization group. If the value of the coupling at that point is less than one (i.e. one can perform perturbation theory in weak coupling), then the fixed point is called a Banks–Zaks fixed point. The existence of the fixed point was first reported in 1974 by Alexander Belavin and Alexander A. Migdal and by William E. Caswell, and later used by Tom Banks and Alex Zaks in their analysis of the phase structure of vector-like gauge theories with massless fermions. The name Caswell–Banks–Zaks fixed point is also used.