On Non-Minimal Couplings to Gravity and Axion Isocurvature Bounds
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arXiv
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| Hauptverfasser: | , |
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| Format: | Preprint |
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2025
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| _version_ | 1866912773765595136 |
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| author | Rigouzzo, Claire Zell, Sebastian |
| author_facet | Rigouzzo, Claire Zell, Sebastian |
| contents | For axions present during inflation, it has been shown that a non-minimal coupling $ξ_σ$ of the inflaton to gravity worsens isocurvature bounds, while a non-minimal coupling $ξ_ρ$ of the radial Peccei-Quinn field can alleviate them. We analyze the simultaneous presence of both couplings and determine when one effect dominates the other, in both the metric and Palatini formulations of gravity. The two tendencies interpolate smoothly, but introducing a non-minimal inflaton coupling reduces the viable interval of $ξ_ρ$ in which isocurvature bounds can be alleviated while avoiding backreaction on the inflationary dynamics. We illustrate our findings in Palatini Higgs inflation and Starobinsky inflation. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2512_16754 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | On Non-Minimal Couplings to Gravity and Axion Isocurvature Bounds Rigouzzo, Claire Zell, Sebastian High Energy Physics - Phenomenology Cosmology and Nongalactic Astrophysics General Relativity and Quantum Cosmology High Energy Physics - Theory For axions present during inflation, it has been shown that a non-minimal coupling $ξ_σ$ of the inflaton to gravity worsens isocurvature bounds, while a non-minimal coupling $ξ_ρ$ of the radial Peccei-Quinn field can alleviate them. We analyze the simultaneous presence of both couplings and determine when one effect dominates the other, in both the metric and Palatini formulations of gravity. The two tendencies interpolate smoothly, but introducing a non-minimal inflaton coupling reduces the viable interval of $ξ_ρ$ in which isocurvature bounds can be alleviated while avoiding backreaction on the inflationary dynamics. We illustrate our findings in Palatini Higgs inflation and Starobinsky inflation. |
| title | On Non-Minimal Couplings to Gravity and Axion Isocurvature Bounds |
| topic | High Energy Physics - Phenomenology Cosmology and Nongalactic Astrophysics General Relativity and Quantum Cosmology High Energy Physics - Theory |
| url | https://arxiv.org/abs/2512.16754 |