The Parameterized Post-Friedmannian Framework for Nonminimal Derivative Coupling with General Cosmological Perturbation Metric

Abstract

We study the parameterization of cosmological model where derivative of an additional scalar field coupled to curvature tensor. We extend the Parameterized Post-Friedmannian framework for interacting dark energy theories to the model. Starting from general cosmological perturbation metric, we derive perturbed energy-momentum tensor for scalar field and parameterized the tensor. Based on the value of the parameters, we compare the model with relevant models in current literature. As the results, we find that parameterization for type 1 theories of dark energy which is explicitly coupled to dark matter, gives only 4 non-zero Parameterized Post-Friedmannian coefficients.

An An Interacting Dark Energy Model with Nonminimal Derivative Coupling in the Parameterized Post-Friedmannian Framework

“…For type 1 with NMDC, we have 3 values of A whose coefficient is not zero and only 1 non-zero B coefficient. This results corresponding with previous work [12]. In particular, from all the cases we studied, the coeffients A1, A6, B1, B2, and B4 were always zero.…”

“…In this paper, we adopt the PPF formalism with nonminimal derivative coupling (NMDC) of scalar field as in the previous work [12]. We apply the interacting term between the dark sector to reduce the coincidence problem [13].…”