Spontaneous CP violation in the left-right model and the kaon system
  A left-right model with spontaneous $CP$ breakdown, consistent with the particle physics phenomenology, is presented. Constraints on free parameters of the model: mass of the new right handed gauge boson $M_2$ and ratio $r$ of the two vacuum expectation values of the bidoublet, are found from the measurement of $\epsilon$ in the kaon system. For most of the parameter space, $M_2$ is restricted to be below 10 TeV. Higher masses can be achieved only by fine tuning of Kobayashi-Maskawa matrix elements, quark masses, $r$ and the phase $\alpha$ which is the unique source of $CP$-violation in the model. Large number of combinations of signs of quark masses, which are observables of the model, are found to be not allowed since they contradict with data. The range of $\epsilon'/\epsilon$ the model predicts is around $10^{-4}$ in magnitude. 
G. Barenboim, J. Bernabeu and M. Raidal