Modified Gravity Framework for the Woods-Saxon Inflation: Theoretical Foundations and Observational Constraints
Abstract
We investigate an inflationary scenario within a modified gravity theory that extends the Einstein-Hilbert action through a non-minimal coupling between the inflaton ϕ and the trace of the energy-momentum tensor T. This f(ϕ)T framework is designed to naturally recover the standard general relativity in the post-inflationary universe. Within this theory, we apply the Woods-Saxon potential. The slow-roll dynamics yields a luminal sound speed cs2=1 for our specific choice of the coupling function. For the model parameters a ≲ 1 and the modest coupling β=0.1, we obtain a scalar spectral index ns≈0.959--$0.966$ and a tensor-to-scalar ratio r<0.01, which reveal a good agreement with the latest Planck and BICEP/Keck data on the (ns, r) constraints. Crucially, we shall demonstrate that the f(ϕ)T coupling is essential for the observational viability of the model with respect to the CMB two-point statistics. This work establishes a viable inflationary scenario within the scope of the inflationary observables which are considered here.
Versions
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BibTeX
@misc{younesizadeh2026modified,
title = {{Modified Gravity Framework for the Woods-Saxon Inflation: Theoretical Foundations and Observational Constraints}},
author = {Feyzollah Younesizadeh and Davoud Kamani and Younes Younesizadeh},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.22933},
eprint = {2609.22933},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.22933},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Modified Gravity Framework for the Woods-Saxon Inflation: Theoretical Foundations and Observational Constraints
AU - Feyzollah Younesizadeh
AU - Davoud Kamani
AU - Younes Younesizadeh
PY - 2026
DA - 2026/09/19
PB - arXiv
DO - 10.48550/arxiv.2609.22933
UR - https://arxiv.org/abs/2609.22933
AB - We investigate an inflationary scenario within a modified gravity theory that extends the Einstein-Hilbert action through a non-minimal coupling between the inflaton ϕ and the trace of the energy-momentum tensor T. This f(ϕ)T framework is designed to naturally recover the standard general relativity in the post-inflationary universe. Within this theory, we apply the Woods-Saxon potential. The slow-roll dynamics yields a luminal sound speed c_s^2=1 for our specific choice of the coupling function. For the model parameters a ≲ 1 and the modest coupling β=0.1, we obtain a scalar spectral index n_s≈0.959--$0.966$ and a tensor-to-scalar ratio r<0.01, which reveal a good agreement with the latest Planck and BICEP/Keck data on the (n_s, r) constraints. Crucially, we shall demonstrate that the f(ϕ)T coupling is essential for the observational viability of the model with respect to the CMB two-point statistics. This work establishes a viable inflationary scenario within the scope of the inflationary observables which are considered here.
ER -