Screenings in Modified Gravity: a perturbative approach

Understand

We present a formalism to study screening mechanisms in modified theories of gravity via perturbative methods in different cosmological scenarios.

• We consider Einstein frame posed theories that are recast as Jordan frame theories, where a known formalism is employed, though the resulting non-linearities of the Klein-Gordon equation acquire an explicit coupling between matter and the scalar field, which is not present in Jordan frame theories.
• The obtained growth functions are then separated in screening and non-screened contributions to facilitate its analysis.
• This allows us to compare several theoretical models and to recognize patterns which can be used to differentiate models and their screening mechanisms.