A critical value of the inflationary tensor-to-scalar ratio from inhomogeneous inflation
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arXiv
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| Autori principali: | , , , |
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| Natura: | Preprint |
| Pubblicazione: |
2025
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| _version_ | 1866917147737849856 |
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| author | Giannadakis, Panagiotis Elley, Matthew Flauger, Raphael Lim, Eugene A. |
| author_facet | Giannadakis, Panagiotis Elley, Matthew Flauger, Raphael Lim, Eugene A. |
| contents | We show that, for a given fixed value of the number of e-folds of the homogeneous solution, inflation succeeds with order unity inhomogeneities in the initial conditions above a characteristic value of the tensor-to-scalar ratio $r$. In practice, we work with an $α$-attractor $T$-model and vary its characteristic scale $μ$, keeping the initial inhomogeneities in both gradient and kinetic fields of order unity of the inflationary energy scale. Under these conditions, and assuming 100 e-folds for the homogeneous solution, the requirement for 60 e-folds of inflation occurs at a critical characteristic scale $μ_{crit} \approx 0.02m_{P}$, corresponding to an $r_{crit} \approx 10^{-6}$. Since increasing the amplitude of the inhomogeneities will make inflation less robust and hence require a higher characteristic scale in order for inflation to succeed, for a given number of e-folds achieved by the homogeneous solution $r_{crit}$ is a lower bound. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2512_13673 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | A critical value of the inflationary tensor-to-scalar ratio from inhomogeneous inflation Giannadakis, Panagiotis Elley, Matthew Flauger, Raphael Lim, Eugene A. Cosmology and Nongalactic Astrophysics We show that, for a given fixed value of the number of e-folds of the homogeneous solution, inflation succeeds with order unity inhomogeneities in the initial conditions above a characteristic value of the tensor-to-scalar ratio $r$. In practice, we work with an $α$-attractor $T$-model and vary its characteristic scale $μ$, keeping the initial inhomogeneities in both gradient and kinetic fields of order unity of the inflationary energy scale. Under these conditions, and assuming 100 e-folds for the homogeneous solution, the requirement for 60 e-folds of inflation occurs at a critical characteristic scale $μ_{crit} \approx 0.02m_{P}$, corresponding to an $r_{crit} \approx 10^{-6}$. Since increasing the amplitude of the inhomogeneities will make inflation less robust and hence require a higher characteristic scale in order for inflation to succeed, for a given number of e-folds achieved by the homogeneous solution $r_{crit}$ is a lower bound. |
| title | A critical value of the inflationary tensor-to-scalar ratio from inhomogeneous inflation |
| topic | Cosmology and Nongalactic Astrophysics |
| url | https://arxiv.org/abs/2512.13673 |