Big Axions

Abstract

We introduce big axions: axion models in which a Nambu-Goldstone mode emerges from the collective spontaneous breaking of a network of U(1) symmetries delocalized in theory space. Big axions naturally realize high-quality accidental global symmetries, admit both pre- and post-inflationary cosmological histories, and exhibit rich topological structures that interpolate between ordinary Peccei-Quinn axions and axions which descend from extra-dimensional gauge fields. We identify a minimal phenomenologically viable subclass, little big axions, and demonstrate that they provide a robust solution to the strong charge-parity problem in quantum chromodynamics while potentially accounting for some or all of the dark matter of the universe.