Radiative corrections to theta term in the left-right supersymmetric models

Abstract

We calculate the radiative correction to the theta term in the generic left-right supersymmetric model due to the Kobayashi-Maskawa source of CP-violation. We found that the value of $\bar{\theta}$ is very sensitive to the relations between vacuum expectation values of bidoublet scalars $<\Phi_1> = diag(\kappa_1, \kappa_1')$ and $<\Phi_2> = diag(\kappa_2', \kappa_2)$. The minimal value of $\bar{\theta}$ in the model is found to be of order $10^{-9}$ for $\kappa_1/\kappa_2\sim 1$, $\kappa_1'=\kappa_2'=0$ in agreement with the experimental constraint without an axion mechanism or fine tuning. In other regions of the parameter space, the radiatively induced $\bar{\theta}$ gives unacceptably large contributions to the electric dipole moment of the neutron.