Beyond the Chameleon Mechanism

TL;DR

This paper discusses how non-linear self-interactions in chameleon theories weaken the constraints on the fifth force, allowing for stronger matter coupling without conflicting with existing experiments and observations.

Contribution

It reveals that in chameleon models, the fifth force becomes independent of coupling strength for thin-shell bodies, relaxing previous experimental bounds.

Findings

Fifth force between thin-shell bodies is independent of coupling strength.

Constraints from terrestrial tests and cosmology can be exponentially relaxed.

Chameleon theories can accommodate stronger matter couplings than previously thought.

Abstract

As a result of non-linear self-interactions, in chameleon theories where the field couples to matter much more strongly than gravity does, the fifth force between two bodies with thin-shell is independent of their coupling to the field. As a consequence the bounds on the coupling coming from terrestrial tests of gravity, measurements of the Casimir force and those constraints imposed by the physics of compact objects, big-bang nucleosynthesis and measurements of the cosmic microwave background anisotropies can be exponentially relaxed.