| Abstract: |
The Peccei-Quinn (PQ) invariant extension of the Standard Model naturally explains why the strong interaction does not break CP. In addition, the axion, which appears after spontaneous PQ symmetry breaking, can account for the dark matter of the Universe. We will discuss cosmological constraints on the axion in high scale inflation, where the axion can give a sizable contribution to isocurvature density perturbation. We will also discuss the origin of PQ symmetry in string compactification models. |
