Formalizing slow-roll inflation in scalar-tensor theories of gravitation

Akin K., Arapoğlu A. S. , Yükselci A. E.

PHYSICS OF THE DARK UNIVERSE, vol.30, 2020 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 30
  • Publication Date: 2020
  • Doi Number: 10.1016/j.dark.2020.100691


The viability of slow-roll approximation is examined by considering the structure of phase spaces in scalar-tensor theories of gravitation and the analysis is exemplified with a nonminimally coupled scalar field to the spacetime curvature. The slow-roll field equations are obtained in the Jordan frame in two ways: first using the direct generalization of the slow-roll conditions in the minimal coupling case to nonminimal one, and second, conformal transforming the slow-roll field equations in the Einstein frame to the Jordan frame and then applying the generalized slow-roll conditions. Two inflationary models governed by the potentials V(phi) alpha phi(2) and V(phi) alpha phi(4) are considered to compare the outcomes of two methods based on the analysis of n(s) and r values in the light of recent observational data. (c) 2020 Elsevier B.V. All rights reserved.