Light QCD Axion Dark Matter from Double Level Crossings

Author:

Hai-Jun Li, Ying-Quan Peng, Wei Chao, Yu-Feng Zhou

Keyword:

High Energy Physics - Phenomenology, High Energy Physics - Phenomenology (hep-ph), Cosmology and Nongalactic Astrophysics (astro-ph.CO)

journal:

ITP-23-205, BNU-23-121

date:

2023-10-02 16:00:00

Abstract

The even light QCD axion called the $Z_{\mathcal N}$ axion can both solve the strong CP problem and account for the dark matter (DM). We point out that the double level crossings can naturally take place in the mass mixing between the $Z_{\mathcal N}$ axion and axionlike particle (ALP). The first level crossing occurs much earlier than the QCD phase transition, while the second level crossing occurs exactly during the QCD phase transition if it exists. The $Z_{\mathcal N}$ axion DM relic density can be suppressed or enhanced in the single level crossing, and suppressed in the double level crossings, depending on the onset of axion oscillations. The future axion experiments can detect these level crossing effects.

PDF: Light QCD Axion Dark Matter from Double Level Crossings.pdf