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| Format: | Preprint |
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2026
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| Online Access: | https://arxiv.org/abs/2604.26156 |
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| _version_ | 1866911630589165568 |
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| author | Mavoa, F. Barry, M. B. Ndioukane, R. Ganiou, M. G. Ahloui, F. K. |
| author_facet | Mavoa, F. Barry, M. B. Ndioukane, R. Ganiou, M. G. Ahloui, F. K. |
| contents | In this work, we investigated several inflationary scenarios within the framework of modified $f(Q,ϕ)$ gravity with a nonminimal coupling between the scalar field and the nonmetricity scalar. We focused on the impact of the coupling parameter $ξ$ on the inflationary observables, namely the scalar spectral index $n_s$ and the tensor-to-scalar ratio $r$. In the case of De Sitter inflation, we showed that the model can reproduce observationally viable predictions only within a restricted range of the coupling parameter. Specifically, we found that $n_s$ increases with $ξ$, while $r$ decreases, leading to a narrow allowed region $10^{-3} \lesssim ξ\lesssim 10^{-2}$ compatible with Planck data. Outside this range, the model either predicts excessively large tensor modes or an unphysical blue-tilted spectrum. We also derived theoretical constraints on $ξ$ from the consistency of the model, leading to an upper bound $ξ< \fracκ{2p}$. For $κ= 1$ and $p = 60$, this implies $ξ< 0.00833$, with a preferred region around $ξ\sim \mathcal{O}(10^{-3})$. Furthermore, we analyzed the Cosh-type inflationary model and showed that it provides a robust and consistent description of inflation. In this case, the tensor-to-scalar ratio decreases while the scalar spectral index increases with the number of e-folds $N$. For $N = 60$, the model predicts $n_s \approx 0.965 - 0.967, \qquad r \approx 0.017 - 0.018$, in excellent agreement with current observational constraints. Overall, our results highlight the crucial role of the nonminimal coupling in shaping the inflationary dynamics and ensuring compatibility with cosmological observations. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2604_26156 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Inflationary Scenarios in $f(Q,ϕ)$ Gravity with Scalar Field Coupling Mavoa, F. Barry, M. B. Ndioukane, R. Ganiou, M. G. Ahloui, F. K. General Relativity and Quantum Cosmology In this work, we investigated several inflationary scenarios within the framework of modified $f(Q,ϕ)$ gravity with a nonminimal coupling between the scalar field and the nonmetricity scalar. We focused on the impact of the coupling parameter $ξ$ on the inflationary observables, namely the scalar spectral index $n_s$ and the tensor-to-scalar ratio $r$. In the case of De Sitter inflation, we showed that the model can reproduce observationally viable predictions only within a restricted range of the coupling parameter. Specifically, we found that $n_s$ increases with $ξ$, while $r$ decreases, leading to a narrow allowed region $10^{-3} \lesssim ξ\lesssim 10^{-2}$ compatible with Planck data. Outside this range, the model either predicts excessively large tensor modes or an unphysical blue-tilted spectrum. We also derived theoretical constraints on $ξ$ from the consistency of the model, leading to an upper bound $ξ< \fracκ{2p}$. For $κ= 1$ and $p = 60$, this implies $ξ< 0.00833$, with a preferred region around $ξ\sim \mathcal{O}(10^{-3})$. Furthermore, we analyzed the Cosh-type inflationary model and showed that it provides a robust and consistent description of inflation. In this case, the tensor-to-scalar ratio decreases while the scalar spectral index increases with the number of e-folds $N$. For $N = 60$, the model predicts $n_s \approx 0.965 - 0.967, \qquad r \approx 0.017 - 0.018$, in excellent agreement with current observational constraints. Overall, our results highlight the crucial role of the nonminimal coupling in shaping the inflationary dynamics and ensuring compatibility with cosmological observations. |
| title | Inflationary Scenarios in $f(Q,ϕ)$ Gravity with Scalar Field Coupling |
| topic | General Relativity and Quantum Cosmology |
| url | https://arxiv.org/abs/2604.26156 |