The quality/cosmology tension for a post-inflation QCD axion
It is difficult to construct a post-inflation QCD axion model that solves the axion quality problem (and hence the Strong CP problem) without introducing a cosmological disaster. In a post-inflation axion model, the axion field value is randomized during the Peccei-Quinn phase transition, and axion...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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Springer Science and Business Media LLC
2024
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| Online Access: | https://hdl.handle.net/1721.1/155806 |
| _version_ | 1824458021404672000 |
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| author | Lu, Qianshu Reece, Matthew Sun, Zhiquan |
| author2 | Massachusetts Institute of Technology. Center for Theoretical Physics |
| author_facet | Massachusetts Institute of Technology. Center for Theoretical Physics Lu, Qianshu Reece, Matthew Sun, Zhiquan |
| author_sort | Lu, Qianshu |
| collection | MIT |
| description | It is difficult to construct a post-inflation QCD axion model that solves the axion quality problem (and hence the Strong CP problem) without introducing a cosmological disaster. In a post-inflation axion model, the axion field value is randomized during the Peccei-Quinn phase transition, and axion domain walls form at the QCD phase transition. We emphasize that the gauge equivalence of all minima of the axion potential (i.e., domain wall number equals one) is insufficient to solve the cosmological domain wall problem. The axion string on which a domain wall ends must exist as an individual object (as opposed to a multi-string state), and it must be produced in the early universe. These conditions are often not satisfied in concrete models. Post-inflation axion models also face a potential problem from fractionally charged relics; solving this problem often leads to low-energy Landau poles for Standard Model gauge couplings, reintroducing the quality problem. We study several examples, finding that models that solve the quality problem face cosmological problems, and vice versa. This is not a no-go theorem; nonetheless, we argue that it is much more difficult than generally appreciated to find a viable post-inflation QCD axion model. Successful examples may have a nonstandard cosmological history (e.g., multiple types of cosmic axion strings of different tensions), undermining the widespread expectation that the post-inflation QCD axion scenario predicts a unique mass for axion dark matter. |
| first_indexed | 2024-09-23T10:27:35Z |
| format | Article |
| id | mit-1721.1/155806 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2025-02-19T04:19:16Z |
| publishDate | 2024 |
| publisher | Springer Science and Business Media LLC |
| record_format | dspace |
| spelling | mit-1721.1/1558062024-12-23T04:56:15Z The quality/cosmology tension for a post-inflation QCD axion Lu, Qianshu Reece, Matthew Sun, Zhiquan Massachusetts Institute of Technology. Center for Theoretical Physics It is difficult to construct a post-inflation QCD axion model that solves the axion quality problem (and hence the Strong CP problem) without introducing a cosmological disaster. In a post-inflation axion model, the axion field value is randomized during the Peccei-Quinn phase transition, and axion domain walls form at the QCD phase transition. We emphasize that the gauge equivalence of all minima of the axion potential (i.e., domain wall number equals one) is insufficient to solve the cosmological domain wall problem. The axion string on which a domain wall ends must exist as an individual object (as opposed to a multi-string state), and it must be produced in the early universe. These conditions are often not satisfied in concrete models. Post-inflation axion models also face a potential problem from fractionally charged relics; solving this problem often leads to low-energy Landau poles for Standard Model gauge couplings, reintroducing the quality problem. We study several examples, finding that models that solve the quality problem face cosmological problems, and vice versa. This is not a no-go theorem; nonetheless, we argue that it is much more difficult than generally appreciated to find a viable post-inflation QCD axion model. Successful examples may have a nonstandard cosmological history (e.g., multiple types of cosmic axion strings of different tensions), undermining the widespread expectation that the post-inflation QCD axion scenario predicts a unique mass for axion dark matter. 2024-07-30T19:25:38Z 2024-07-30T19:25:38Z 2024-07-24 2024-07-28T03:25:35Z Article http://purl.org/eprint/type/JournalArticle 1029-8479 https://hdl.handle.net/1721.1/155806 Lu, Q., Reece, M. & Sun, Z. The quality/cosmology tension for a post-inflation QCD axion. J. High Energ. Phys. 2024, 227 (2024). PUBLISHER_CC en 10.1007/jhep07(2024)227 Journal of High Energy Physics Creative Commons Attribution https://creativecommons.org/licenses/by/4.0/ The Author(s) application/pdf Springer Science and Business Media LLC Springer Berlin Heidelberg |
| spellingShingle | Lu, Qianshu Reece, Matthew Sun, Zhiquan The quality/cosmology tension for a post-inflation QCD axion |
| title | The quality/cosmology tension for a post-inflation QCD axion |
| title_full | The quality/cosmology tension for a post-inflation QCD axion |
| title_fullStr | The quality/cosmology tension for a post-inflation QCD axion |
| title_full_unstemmed | The quality/cosmology tension for a post-inflation QCD axion |
| title_short | The quality/cosmology tension for a post-inflation QCD axion |
| title_sort | quality cosmology tension for a post inflation qcd axion |
| url | https://hdl.handle.net/1721.1/155806 |
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