Large-scale structure in brane-induced gravity. I. Perturbation theory
- Center for Cosmology and Particle Physics, Department of Physics, New York University, New York 10003, New York (United States)
We study the growth of subhorizon perturbations in brane-induced gravity using perturbation theory. We solve for the linear evolution of perturbations taking advantage of the symmetry under gauge transformations along the extra-dimension to decouple the bulk equations in the quasistatic approximation, which we argue may be a better approximation at large scales than thought before. We then study the nonlinearities in the bulk and brane equations, concentrating on the workings of the Vainshtein mechanism by which the theory becomes general relativity (GR) at small scales. We show that at the level of the power spectrum, to a good approximation, the effect of nonlinearities in the modified gravity sector may be absorbed into a renormalization of the gravitational constant. Since the relation between the lensing potential and density perturbations is entirely unaffected by the extra physics in these theories, the modified gravity can be described in this approximation by a single function, an effective gravitational constant for nonrelativistic motion that depends on space and time. We develop a resummation scheme to calculate it, and provide predictions for the nonlinear power spectrum. At the level of the large-scale bispectrum, the leading order corrections are obtained by standard perturbation theory techniques, and show that the suppression of the brane-bending mode leads to characteristic signatures in the non-Gaussianity generated by gravity, generic to models that become GR at small scales through second-derivative interactions. We compare the predictions in this work to numerical simulations in a companion paper.
- OSTI ID:
- 21308623
- Journal Information:
- Physical Review. D, Particles Fields, Vol. 80, Issue 10; Other Information: DOI: 10.1103/PhysRevD.80.104006; (c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
APPROXIMATIONS
BRANES
COMPARATIVE EVALUATIONS
COMPUTERIZED SIMULATION
CORRECTIONS
DENSITY
DISTURBANCES
EQUATIONS
EVOLUTION
FORECASTING
GAUGE INVARIANCE
GENERAL RELATIVITY THEORY
GRAVITATION
INTERACTIONS
NONLINEAR PROBLEMS
PERTURBATION THEORY
POTENTIALS
RENORMALIZATION
SPECTRA
SYMMETRY