Scalar Field Assisted $f(R)$ Gravity Inflation

Abstract

In this paper we investigate the inflationary dynamics of an $f(R)$ gravity in the presence of a canonical scalar field. We specifically choose the cosmological evolution to be a quasi-de Sitter evolution and also the $f(R)$ gravity is assumed to be a modified version of the $R^2$ gravity. We investigate which scalar field potential can produce the quasi-de Sitter evolution for the choice of the $f(R)$ gravity we made, and also we study in detail the inflationary dynamics of the resulting theory. As we demonstrate, the spectral index is identical to the one corresponding to the ordinary $R^2$ gravity, while the scalar-to-tensor ratio is found to be smaller than the $R^2$ inflation one consequently, compatibility with both the Planck 2015 and BICEP2/Keck-Array data is achieved.

References in corpus (6)

• Unified cosmic history in modified gravity: from F(R) theory to Lorentz non-invariant models
• Modified Gravity Theories on a Nutshell: Inflation, Bounce and Late-time Evolution
• The Standard Model Higgs boson as the inflaton
• Inflationary Cosmology
• Inflationary $\alpha$-attractors from $F(R)$ Gravity
• Viable Mimetic Completion of Unified Inflation-Dark Energy Evolution in Modified Gravity

Cited by in corpus (5)

• Effects of Spatial Curvature on the $f(R)$ Gravity Phase Space: no Inflationary Attractor?
• Swampland dS conjecture in Mimetic $f(R,T)$ gravity
• Autonomous Dynamical System Description of de Sitter Evolution in Scalar Assisted $f(R)-\varphi$ Gravity
• Inflation in mimetic $f(R,T)$ gravity
• Intermediate Coupling Regime in Dilatonic $f(R,T)$ Inflationary Universe