2025/07/06 by Xiangwei Yin, Cheng-Wei Chiang, Yin, Xiangwei +5
Physics and Astronomy · #Advanced Thermodynamics and Statistical Mechanics #Cosmology and Gravitation Theories #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #Statistical Mechanics and Entropy
paper · pdf · doi:10.48550/arxiv.2507.04281
openalex publication_date 2025/07/06 · openalex created_date 2025/10/20 · openalex updated_date 2026/07/28
The clockwork framework can realize TeV-scale U(1)PQ symmetry breaking while generating a large axion decay constant \(fa\). We propose a minimal clockwork axion model with three scalar fields, in which two domain walls (DWs) have non-zero tension. The DW associated with one of the fields is formed following the Peccei-Quinn (PQ) symmetry breaking and subsequently collapses due to the potential bias induced by the QCD instanton. The nano-hertz stochastic gravitational waves (GWs) generated from this DW annihilation can be probed by Pulsar Timing Arrays experiments. In addition, the DW related to the other field is annihilated by a bias potential originating from higher-dimensional operators, producing a significant GW signal with a peak frequency around \(9.41×10-5\) Hz, which can be detected by the LISA, Taiji, and TianQin experiments. Constraints on the model from SN1987, dark matter overproduction, Big Bang Nucleosynthesis, cosmic microwave background, and primordial black holes have been considered. The relic density of QCD axion dark matter can be explained through the misalignment mechanism.