Axion production via trapped misalignment from Peccei-Quinn symmetry breaking

TL;DR

This paper explores how small PQ symmetry-breaking effects influence axion production, revealing a trapped misalignment mechanism that extends the axion mass range for dark matter, with testable experimental implications.

Contribution

It introduces a novel trapped misalignment mechanism affected by PQ-breaking operators, expanding the viable axion dark matter mass window beyond previous limits.

Findings

Delayed axion oscillation onset due to trapped misalignment

Extended axion mass window for dark matter ($m_a \,\gg\ 10^{-5}$ eV)

Testability through multiple experimental searches

Abstract

The Peccei-Quinn (PQ) symmetry does not need to be exact, and even a tiny source of PQ breaking not aligned with the QCD anomaly might have significant phenomenological implications. In this study, we examine the effects of a general class of PQ-breaking operators on the axion cosmological production via misalignment, focussing on both temperature-dependent and independent PQ-breaking potentials. In particular, we show that a variant of the trapped misalignment mechanism can delay the onset of axion oscillation, leading to an axion dark matter window with $m_a \gg 10^{-5}$ eV. This scenario is testable through various experimental approaches, including standard axion haloscopes and helioscopes, as well as searches for electric dipole moments and axion-mediated forces.