More accurate slow-roll approximations for inflation in scalar-tensor theories

2025/02/18 by E. O. Pozdeeva, Maria A. Skugoreva, Pozdeeva, Ekaterina O. +5 · 2 citations
Earth and Planetary Sciences · Physics and Astronomy · #Cosmology and Gravitation Theories #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #Geophysics and Gravity Measurements #Mathematical Physics (math-ph) #Solar and Space Plasma Dynamics

paper · pdf · doi:10.48550/arxiv.2502.13008

openalex publication_date 2025/02/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

We propose new versions of the slow-roll approximation for inflationary models with nonminimally coupled scalar fields. We derive more precise expressions for the standard slow-roll parameters as functions of the scalar field. To verify the accuracy of the proposed approximations, we consider inflationary models with the induced gravity term and the fourth-order monomial potential. For specific values of the model parameters, this model is the well-known Higgs-driven inflationary model. We investigate the inflationary dynamics in the Jordan frame and come to the conclusion that the proposed versions of the slow-roll approximation are not only more accurate at the end of inflation, but also give essentially more precise estimations for the tensor-to-scalar ratio r and the amplitude of scalar perturbations A_s.

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