2023/07/10 by Michael Dine, Dine, Michael
Physics and Astronomy · #Astronomy and Astrophysical Research #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #High Energy Physics - Theory (hep-th)
paper · pdf · doi:10.48550/arxiv.2307.04710
openalex publication_date 2023/07/10 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
Theories in which the Peccei-Quinn phase transition occurs after inflation tend to suffer from problematic domain walls. One possible solution involves a small, explicit breaking ot the symmetry. But this raises other potential issues. We review some aspects of axion domain walls, focussing especially on this proposed solution. We argue, in disagreement with some recent literature, that there is little axion radiation from the system until the domains actually collapse. The same applies to gravitational waves and electromagnetic radiation. The final stages of the collapse yields small numbers of extremely energetic axions, which interact only rarely with ordinary matter, and are thus relatively harmless. We then note that, if one accepts a remarkable coincidence, this solution can be acceptable. We consider a possible explanation of the required coincidence