Transit cosmological models coupled with zero-mass scalar-field with high redshift in higher derivative theory

TL;DR

This paper explores flat FRW cosmological models with a zero-mass scalar field in higher derivative gravity, presenting accelerating and transit models consistent with observations and analyzing their physical parameters.

Contribution

It introduces new cosmological models involving zero-mass scalar fields in higher derivative gravity, including transit phase models with observationally consistent parameters.

Findings

Transit redshift z_t=0.414 matches observations

EoS parameter crosses -1, indicating phantom behavior

Models yield universe age consistent with current estimates

Abstract

The present study deals with a flat FRW cosmological model filled with perfect fluid coupled with the zero-mass scalar field in the higher derivative theory of gravity. We have obtained two types of universe models, the first one is the accelerating universe (power-law cosmology) and the second one is the transit phase model (hyperbolic expansion-law). We have obtained various physical and kinematic parameters and discussed them with observationally constrained values of $H_{0}$. The transit redshift value is obtained $z_{t}=0.414$ where the transit model shows signature-flipping and is consistent with recent observations. In our models, the present values of EoS parameter $\omega_{0}$ crosses the cosmological constant value $\omega_{0}=-1$. Also, the present age of the universe is calculated.