Cosmic analysis of a model in higher-order gravity theory

The late-time cosmic acceleration is investigated in modified gravity theory with higher-order curvature terms of the Ricci scalar and the Gauss–Bonnet invariant. The gravitational field equation is analyzed with an appropriate parameterization of the Hubble parameter and the cosmological constraints on model parameters are derived by using the Hubble, Pantheon, and their joint dataset. It is demonstrated that the best-fit values of the model parameters are in close agreement with the recent observations. Moreover, it is shown that the deceleration parameter transits from the decelerating to an accelerating phase in the late-time universe and that the equation of state parameter converges to the quintessence region and the accelerated expansion of the universe is realized. Furthermore, the perturbation analysis has been performed concerning the Hubble parameter and the energy density to examine the stability conditions of the model under the observational constraints. The energy conditions, the statefinder diagnostic, and the description of a scalar field theory are also investigated.