A study of perturbations in scalar-tensor theory using 1+3 covariant approach

Understand

This work discusses scalar-tensor theories of gravity, with a focus on the Brans-Dicke subclass, and one that also takes note of the latter's equivalence with $f(R)$ gravitation theories.

• A 1+3 covariant formalism is used in this case to discuss covariant perturbations on a background Friedmann-Laimaitre-Robertson-Walker (FLRW) space-time.
• Linear perturbation equations are developed, based on gauge-invariant gradient variables.
• Both scalar and harmonic decompositions are applied to obtain second-order equations.