Quark mass uncertainties revive KSVZ axion dark matter

TL;DR

This paper demonstrates that uncertainties in light quark masses can relax experimental bounds on KSVZ axion dark matter, allowing certain axion mass ranges to evade current detection limits and potentially constitute all galactic dark matter.

Contribution

It reveals how the Kaplan-Manohar ambiguity in quark masses impacts axion constraints, opening new parameter space for axion dark matter models.

Findings

KSVZ axions in the 2-3 μeV range can evade ADMX bounds

Quark mass uncertainties affect axion mass constraints

Axions could make up 100% of galactic dark matter

Abstract

The Kaplan-Manohar ambiguity in light quark masses allows for a larger uncertainty in the ratio of up to down quark masses than naive estimates from the chiral Lagrangian would indicate. We show that it allows for a relaxation of experimental bounds on the QCD axion, specifically KSVZ axions in the $2-3 \mu$eV mass range composing 100% of the galactic dark matter halo can evade the experimental limits placed by the ADMX collaboration.