Scalar field perturbations in Horava-Lifshitz cosmology

Understand

We study perturbations of a scalar field cosmology in Horava-Lifshitz gravity, adopting the most general setup without detailed balance but with the projectability condition.

• We derive the generalized Klein-Gordon equation, which is sixth-order in spatial derivatives.
• Then we investigate scalar field perturbations coupled to gravity in a flat Friedmann-Robertson-Walker background.
• In the sub-horizon regime, the metric and scalar field modes have independent oscillations with different frequencies and phases except in particular cases.