Dynamical Scalar Degree of Freedom in Horava-Lifshitz Gravity
Abstract
We investigate the linear cosmological perturbations of Horava-Lifshitz gravity in a FRW universe without any matter. Our results show that a new gauge invariant dynamical scalar mode emerges, due to the gauge transformation under the "foliation-preserving" diffeomorphism and "projectability condition", and it can produce a scale invariant power spectrum. In the infrared regime with λ=1, the dynamical scalar degree of freedom turns to be a non-dynamical one at the linear order level.
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