Solving the strong CP problem within a minimal extension of the standard model

A minimal extension of the standard model is presented where CP violation is spontaneously broken at a high scale through a phase of a complex singlet scalar S. This phase is sufficient to generate the usual K.M. mechanism in the charged weak interactions. The model provides a simple solution to the strong CP problem. The parameter Θ-bar is zero in tree approximation, and one loop contributions to Θ-bar are suppressed both by Yukawa couplings and by the ratio <φ>2/2. From the limit on Θ-bar derived from the experimental upper bound on the neutron electric dipole moment, one obtains the lower bound ≥ 1 TeV, 100 TeV for Yukawa couplings of the order of 10-2, 10-1 respectively. (author) 16 refs