Spontaneous breaking of the flavor symmetry avoids the strong CP problem

Abstract

A promising approach to the Standard Model flavor puzzle is based on the idea that the $SU(3)^3$ quark-flavor symmetry is spontaneously broken by vacuum expectation values of `Yukawa fields' which minimize the symmetry invariant scalar potential at configurations corresponding to the observed quark masses and mixing angles. We show that this approach provides a simple and elegant explanation for CP conservation in strong interactions.