Theories of Dark Energy with Screening Mechanisms

TL;DR

This review discusses theories of dark energy involving light scalar fields with screening mechanisms, like chameleons and symmetrons, to reconcile long-range forces with local gravity tests.

Contribution

It provides a comprehensive overview of screening mechanisms in dark energy theories, focusing on chameleon and symmetron models, and their role in cosmology.

Findings

Chameleon and symmetron models can screen scalar fields locally.

These models reconcile long-range forces with laboratory and solar system tests.

Screening mechanisms are crucial for consistent dark energy theories.

Abstract

Despite the overwhelming evidence for the existence of dark energy and dark matter, their underlying fundamental physics remains unknown. This review article explores the tantalizing possibility that the dark sector includes new light degrees of freedom that mediate long-range forces on cosmological scales. To ensure consistency with laboratory and solar system tests of gravity, some screening mechanism is necessary to "hide" these degrees of freedom locally. I will focus on two broad classes of screening theories, chameleons and symmetrons, which rely respectively on the scalar field acquiring a large mass or weak coupling in the presence of large ambient matter density.