The Minimal High-Quality QCD Axion
arXiv:2607.08814
Abstract
The canonical QCD axion is minimal but not high quality. We identify a minimal high-quality QCD axion, in which the Peccei-Quinn symmetry emerges as a gauge-origin boundary remnant of five-dimensional gauge invariance on a flat interval, and the axion is the surviving Wilson-line phase. QCD and the Standard Model remain four-dimensional, retaining much of the simplicity of KSVZ/DFSZ anomaly sectors. The construction requires no bulk QCD, warping, or color Chern-Simons term, yet retains exponential quality protection. Thus axion quality is compatible with minimality.
4 pages + 2-page Appendix, 1 table