Perturbed solutions in matter FLRW model with R _{μ ν} R ^{μ ν} and R ⁴ gravity

Abstract

In this paper, we consider the R μ ν R μ ν and R 4 gravity corrections to the general relativity (GR)-based cosmological model, and then apply the perturbation theory to first order to explore the effects of these corrections on the results obtained from the GR-based cosmological model. This cosmological model suggests a small nonzero value (∼10−3) of the equation of State (EoS) parameter (w) of the matter field. We calculate the Hubble parameter and the deceleration parameter using the perturbed solutions of the scale factor, which are in very good agreement with the recent observational data. Additionally, we also explore the validity of the generalized second law of thermodynamics under the R μ ν R μ ν and R 4 gravity theories.