8 papers
Completing Axion Double Level Crossings
Hai-Jun Li, Wei Chao, Huai-Ke Guo +1
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 exc…
Axion Mixing in the String Axiverse
Hai-Jun Li, Yu-Feng Zhou
String axiverse provides a fascinating and complex landscape for axion physics. The requirement in type IIB string axiverse models necessitates at least two axions to ensure the pr…
Axion effects on gamma-ray spectral irregularities. II: Implications of EBL absorption
Hai-Jun Li, Wei Chao, Xiu-Hui Tan +1
The extragalactic background light (EBL) plays a crucial role in the propagation of high-energy particles throughout the Universe. In this work, we explore the impact of the EBL ab…
Mass Mixing between QCD Axions
Hai-Jun Li, Yu-Feng Zhou
We introduce a novel level crossing phenomenon in the mass mixing between the QCD axions, one canonical QCD axion and one axion. The level crossing can take place…
Upper limit on the axion-photon coupling from Markarian 421
Hai-Jun Li, Wei Chao, Yu-Feng Zhou
Markarian 421 is a well-known nearby BL Lac blazar at the redshift . Many previous works were investigated to constrain the axion-photon coupling from its TeV gamma-ray ob…
Gravitational waves and primordial black holes from axion domain walls in level crossing
Hai-Jun Li, Yu-Feng Zhou
In this paper, we investigate the nano-Hertz gravitational waves (GWs) emission and the massive primordial black holes (PBHs) formation from the light QCD axion scenario. We consid…