2009/07/31 by Niayesh Afshordi · 3 citations
Physics and Astronomy · #Advanced Differential Geometry Research #Black Holes and Theoretical Physics #Cosmology and Gravitation Theories #astro-ph.CO #gr-qc #hep-th
paper · pdf · doi:10.1103/physrevd.80.081502
published as Phys.Rev.D80:081502,2009 · 5 pages, 1 figure, added references, submitted to PRD
arxiv created 2009/08/07 · openalex publication_date 2009/10/30 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Ho\ifmmode \checkr\else \vr\fiava-Lifshitz theory has been recently put forth as a proposal for a renormalizable theory of quantum gravity [1]. It explicitly breaks Lorentz invariance, introducing an apparent extra scalar degree of freedom. I show that the low energy limit of (non-projectible) Ho\ifmmode \checkr\else \vr\fiava-Lifshitz gravity is uniquely given by the quadratic cuscuton model: a covariant scalar field theory with an infinite speed of sound and a quadratic potential, minimally coupled to Einstein gravity. This implies that the extra scalar is nondynamical to all orders in perturbation theory. Cosmological constraints on the quadratic cuscuton model constrain the low energy Lorentz breaking parameter of Ho\ifmmode \checkr\else \vr\fiava-Lifshitz theory to |\ensuremathλ\ensuremath-1|<0.014. We also point out that the spatial hypersurfaces are constant mean curvature or uniform expansion surfaces and introduce geometrical symmetries that can protect the nondynamical nature of these theories.