Comments on scaling limits of 4d theories

We revisit the study of the maximally singular point in the Coulomb branch of 4d $$ \mathcal{N} = 2 $$ SU(N) gauge theory with Nf = 2n flavors for Nf < 2N. When n ≥ 2, we find that the low-energy physics is described by two non-trivial superconformal field theories coupled to a magnetic SU(2) gauge group which is infrared free. (In the special case n = 2, one of these theories is a theory of free hypermultiplets.) This observation removes a possible counter example to a conjectured a-theorem.