paper

Dynamical reconstruction of the CDM model in the scalar-tensor representation of gravity

arXiv:2410.00707 · doi:10.1140/epjc/s10052-025-13919-2

Abstract

Motivated by the growing interest in the nonmetricity-matter couplings, we develop the scalar-tensor formulation of recently introduced gravity, where is the nonmetricity and is the trace of the energy-momentum tensor. The main properties of the scalar-tensor formalism for the Friedmann-Lema{\^ i}tre-Robertson-Walker (FLRW) Universe are discussed, and we introduce an appropriate set of dynamical variables to analyze the cosmic evolution of the scalar-tensor cosmology as a dynamical system. By considering two distinct cosmic fluids, namely matter and radiation, we have demonstrated that the cosmological phase space exhibits the typical curvature-dominated, radiation-dominated, matter-dominated, and exponentially accelerated fixed points. Furthermore, under an appropriate set of initial conditions compatible with the current observations from the Planck satellite, our analysis shows that the scalar-tensor successfully yields models indistinguishable from the CDM cosmology and compatible with the weak-field solar system dynamics, without the inclusion of a cosmological constant . Thus, the theory introduced herein may be regarded as a suitable candidate to describe the cosmological dynamics of the Universe.

13 pages, 2 figures, 1 table

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