Dark Glueballs and their Ultralight Axions

TL;DR

This paper explores a theoretical model where dark glueballs and ultralight axions from string theory could constitute dark matter, with astrophysical and particle physics constraints shaping their properties.

Contribution

It demonstrates that a confining dark gauge sector can produce ultralight axions and dark glueballs consistent with dark matter observations and string theory parameters.

Findings

Ultralight axions can naturally realize fuzzy dark matter.

Astrophysical data constrains the dark glueball to axion ratio.

Electric dipole moments limit axion mixing with QCD axion.

Abstract

Dark gauge sectors and axions are well-motivated in string theory. We demonstrate that if a confining gauge sector gives rise to dark glueballs that are a fraction of the dark matter, and the associated axion has a decay constant near the string scale, then this axion is ultralight and naturally realizes the fuzzy dark matter scenario with a modest tuning of a temperature ratio. Astrophysical observations constrain the size of the glueball component relative to the axionic component, while electric dipole moments constrain mixing with the QCD axion.