Chameleonic Theories: A Short Review

Understand

In the chameleon mechanism, a field (typically scalar) has a mass that depends on the matter density of the environment: the larger is the matter density, the larger is the mass of the chameleon.

• We briefly review some aspects of chameleonic theories.
• In particular, in a typical class of these theories, we discuss the lagrangian, the role of conformal transformations, the equation of motion and the thin-shell effect.
• We also discuss $f(R)$ theories and chameleonic quantum gravity.