A non-compact QCD axion
Fuente:
arXiv
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| Autori principali: | , , |
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| Natura: | Preprint |
| Pubblicazione: |
2025
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| _version_ | 1866914217279356928 |
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| author | Karananas, Georgios K. Shaposhnikov, Mikhail Zell, Sebastian |
| author_facet | Karananas, Georgios K. Shaposhnikov, Mikhail Zell, Sebastian |
| contents | We investigate the cosmology of an axion that is fundamentally non-compact. During inflation, fluctuations of the effectively massless field populate many QCD vacua, thereby evading conventional isocurvature constraints while generating domain walls -- without accompanying cosmic strings. A small non-QCD contribution to the axion potential is required to trigger the timely collapse of domain walls; as a consequence, a residual amount of CP violation in the strong sector must exist, potentially within reach of planned experiments. Non-compact axions can account for the entirety of the dark matter abundance, and the collapse of domain walls sources a stochastic gravitational-wave background at nanohertz frequencies. Such axion dynamics can be embedded in top-down constructions -- such as Weyl-invariant Einstein-Cartan gravity -- where the tilting of the axion potential arises automatically. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2512_20290 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | A non-compact QCD axion Karananas, Georgios K. Shaposhnikov, Mikhail Zell, Sebastian High Energy Physics - Phenomenology Cosmology and Nongalactic Astrophysics General Relativity and Quantum Cosmology High Energy Physics - Theory We investigate the cosmology of an axion that is fundamentally non-compact. During inflation, fluctuations of the effectively massless field populate many QCD vacua, thereby evading conventional isocurvature constraints while generating domain walls -- without accompanying cosmic strings. A small non-QCD contribution to the axion potential is required to trigger the timely collapse of domain walls; as a consequence, a residual amount of CP violation in the strong sector must exist, potentially within reach of planned experiments. Non-compact axions can account for the entirety of the dark matter abundance, and the collapse of domain walls sources a stochastic gravitational-wave background at nanohertz frequencies. Such axion dynamics can be embedded in top-down constructions -- such as Weyl-invariant Einstein-Cartan gravity -- where the tilting of the axion potential arises automatically. |
| title | A non-compact QCD axion |
| topic | High Energy Physics - Phenomenology Cosmology and Nongalactic Astrophysics General Relativity and Quantum Cosmology High Energy Physics - Theory |
| url | https://arxiv.org/abs/2512.20290 |