Kaon Spontaneous CP Violation Reevaluated
  The CP parameters $\epsilon$ and $\epsilon'/\epsilon$ are calculated in the aspon model of spontaneous CP violation, a model which solves the strong CP problem. A new range for the scale of spontaneous breaking of CP is found. It is shown that $\epsilon'/\epsilon$ is suppressed by $\sim x^2 v^2/(\kappa^2 \sin^5 \theta_C) \sim 5 \times 10^{-3}$ relative to the Standard Model. If experiment finds that $\epsilon'/\epsilon$ is $10^{-4}$ or greater in magnitude, it will mean that the present approach to spontaneous CP violation is excluded. 
Paul H. Frampton and Masayasu Harada