Modified gravity models for inflation with non-minimal coupling trace of energy-momentum tensor of the scalar field and Gauss-Bonnet invariant

Pyotr Tsyba

2026

Full text Open access: Gold Metadata (CSL-JSON)
DOI 10.32523/2616-6836-2026-156-3-26-40
Data confidence 70 medium
How this score is calculated

It is built from checkable properties of the record itself: whether the article has a DOI, how many independent sources confirmed its data, whether the required fields are filled in, and how recent the latest confirmation is. Disagreement between sources and a missing identifier lower it. A value of 80 or above means the record was published without further checking; 60 to 79 means it is published at reduced confidence, with a manual check advisable. A record verified by an editor by hand is never pushed below 90 by a recalculation. This scores our data about the article, not the article itself.

Abstract

The article studies the inflationary properties of a cosmological model with the scalar field containing a non-minimal coupling with a modified Gauss-Bonnet invariant \beta f(G)f(\varphi) and the trace of the energy-momentum tensor of the scalar field \alpha f(\varphi) T in the framework of a flat, homogeneous and isotropic Friedman-Robertson-Walker Universe. To study the inflationary properties of the model, the chaotic potential, the natural potential, and the Starobinsky potential were selected. Within the framework of the slow-rolling approximation and assuming the coupling constants \alpha and \beta to be small ( \alpha<<1 and \beta<<1), generalized expressions for the scalar spectral index n_s and the scalar tensor ratio r are obtained. In the work, the Cobaya cosmology shell for cosmological calculations together with the Polychord sampler was used to calculate the theoretical values of the scalar spectral index and the scalar-tensor ratio and compare them with the observables. It is shown that for the chaotic potential, only the value of the scalar spectral index agrees with the observed data of Planck2018, and the value of the scalar-tensor ratio r exceeds the observed value. For the natural potential and the Starobinsky potential, both values of the inflationary parameters are consistent with observations. It is shown that for the case f(G)=G and all types of potentials, the coupling parameter \alpha is marginalized in each model, and the coupling parameter \beta does not affect the dynamics of inflationary parameters and is not constrained in any way.