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Title: Dark energy or modified gravity? An effective field theory approach

We take an Effective Field Theory (EFT) approach to unifying existing proposals for the origin of cosmic acceleration and its connection to cosmological observations. Building on earlier work where EFT methods were used with observations to constrain the background evolution, we extend this program to the level of the EFT of the cosmological perturbations — following the example from the EFT of Inflation. Within this framework, we construct the general theory around an assumed background which will typically be chosen to mimic ΛCDM, and identify the parameters of interest for constraining dark energy and modified gravity models with observations. We discuss the similarities to the EFT of Inflation, but we also identify a number of subtleties including the relationship between the scalar perturbations and the Goldstone boson of the spontaneously broken time translations. We present formulae that relate the parameters of the fundamental Lagrangian to the speed of sound, anisotropic shear stress, effective Newtonian constant, and Caldwell's varpi parameter, emphasizing the connection to observations. It is anticipated that this framework will be of use in constraining individual models, as well as for placing model-independent constraints on dark energy and modified gravity model building.
Authors:
;  [1] ;  [2] ;  [3]
  1. Center for Radiophysics and Space Research, Cornell University, Ithaca, NY 14853 (United States)
  2. Department of Physics, University of Massachusetts, Amherst, MA 01003 (United States)
  3. Department of Physics, Syracuse University, Syracuse, NY 13244 (United States)
Publication Date:
OSTI Identifier:
22282702
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2013; Journal Issue: 08; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; ANISOTROPY; COSMOLOGICAL CONSTANT; COSMOLOGY; FIELD THEORIES; GOLDSTONE BOSONS; GRAVITATION; INFLATIONARY UNIVERSE; LAGRANGIAN FUNCTION; LIMITING VALUES; NONLUMINOUS MATTER; PERTURBATION THEORY; SOUND WAVES; VELOCITY