Speaker
召丰 康
(N)
Description
PQ solution to the strong CP problem probably encounters the axion domain wall problem. In this article, we propose a simple and testable solution, asumming that the $U(1)_{\rm PQ}$ possesses mixed anomaly to a hidden $SU(N_c)$ color. Then, the axion field receives a new cosine potential from the hidden instantons, which breaks the $Z_{N_{DW}}$ subgroup explicitly. The new potential lifts the vacua degeneracy, but also drives the effective $\theta$ angle away from the origin, re-incuring the strong CP problem. However, we find that the dark QCD scale $\Lambda_d$ within the 0.1 to 10 MeV window survives.
Primary author
召丰 康
(N)
