Does confinement imply CP invariance of the strong interactions?

Abstract

The strong coupling constant 1/g2 and the vacuum angle θ of the SU(3) Yang-Mills theory are investigated in the infrared limit under the renormalization group flow. It is shown that the theory has an infrared attractive fixed point at 1/g2 = θ = 0, which leads to linear confinement and naturally solves the strong CP problem. In particular, any initial value of θ 6= 0 is found to be driven to θ = 0 at macroscopic distances, where quarks and gluons freeze into hadrons by the confinement mechanism.