A Unified Description of Screened Modified Gravity

TL;DR

This paper presents a unified framework for describing various screened modified gravity models, focusing on the scalar field dynamics and enabling reconstruction of potentials and couplings from cosmological data.

Contribution

It introduces a comprehensive parameterization that captures the dynamics of multiple screened modified gravity theories in a unified manner.

Findings

Unified description of chameleon, f(R), dilaton, and symmetron models.

A method to reconstruct potentials and couplings from cosmological evolution.

Application of the framework to specific models demonstrating its effectiveness.

Abstract

We consider modified gravity models driven by a scalar field whose effects are screened in high density regions due to the presence of non-linearities in its interaction potential and/or its coupling to matter. Our approach covers chameleon, f(R) gravity, dilaton and symmetron models and allows a unified description of all these theories. We find that the dynamics of modified gravity are entirely captured by the time variation of the scalar field mass and its coupling to matter evaluated at the cosmological minimum of its effective potential, where the scalar field sits since an epoch prior to Big Bang Nucleosynthesis. This new parameterisation of modified gravity allows one to reconstruct the potential and coupling to matter and therefore to analyse the full dynamics of the models, from the scale dependent growth of structures at the linear level to non-linear effects requiring N-body simulations. This procedure is illustrated with explicit examples of reconstruction for chameleon, dilaton, f(R) and symmetron models.