Solving the Strong CP Problem Without the Peccei-Quinn Symmetry

摘要

We prove a simple theorem about the anti theta parameter in grand unified models with spontaneous CP breaking. This theorem states two conditions on such models which, if fulfilled, imply that anti theta is zero at tree level. Models which fulfill these conditions are generalizations of a recent model of A. Nelson and are easy to construct. 8 references. (ERA citation 10:019411)