Spontaneous CP violation and the strong CP problem

Understand

We derive sufficient conditions that guarantee a robust solution of the strong CP problem in theories with spontaneous CP violation, and introduce a class of models satisfying these requirements.

• In the simplest scenarios the dominant contribution to the topological angle arises at 3-loop order in the Yukawa couplings.
• A variety of realizations are possible on a warped extra dimension, which can simultaneously address the Planck-TeV hierarchy.
• Experimental signatures of this approach to the strong CP problem include flavor violation and vector-like partners of the top or bottom quarks.