Work

Completing axion double level crossings

Year: 2026

Type: article

Abstract: In this work, we present the refinement of axion double level crossings within the context of multi-axion mass mixing, specifically focusing on cases where the number of axions exceeds two. Our investigation reveals that double level crossings are a common phenomenon in the mass mixing of the Z N axion and axion-like particles. Physically, these double level crossings involve a first level crossing at high temperatures followed by a second level crossing induced by the Z N axion mass transition at T QCD . We introduce the general model for double level crossings, along with several toy examples, and redefine the light and heavy axion scenarios. In the light axion scenario, double level crossings can occur multiple times in the large N limit. However, excessively large values of N may also prevent the occurrence of double level crossings. Conversely, in the heavy axion scenario, excessively small N may similarly prevent their occurrence. Our findings also have some intriguing implications for axion cosmology.

Source: Nuclear Physics B

DOI: 10.1016/j.nuclphysb.2026.117455

Authors: Hai-Jun Li, Wei Chao, Huai-Ke Guo, Yu-Feng Zhou

Institutions: Chinese Academy of Sciences, International Centre for Theoretical Physics Asia-Pacific, Institute of Theoretical Physics, Beijing Normal University, University of Chinese Academy of Sciences

Language: English

Topic: Dark Matter and Cosmic Phenomena

Subfield: Nuclear and High Energy Physics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: diamond

Funders: National Natural Science Foundation of China, Chinese Academy of Sciences, National Key Research and Development Program of China, Fundamental Research Funds for the Central Universities