The effective field theory of cosmological large scale structures
Abstract
Large scale structure surveys will likely become the next leading cosmological probe. In our universe, matter perturbations are large on short distances and small at long scales, i.e. strongly coupled in the UV and weakly coupled in the IR. To make precise analytical predictions on large scales, we develop an effective field theory formulated in terms of an IR effective fluid characterized by several parameters, such as speed of sound and viscosity. These parameters, determined by the UV physics described by the Boltzmann equation, are measured from Nbody simulations. We find that the speed of sound of the effective fluid is c_s^2 ≈ {1}{0^{{  {6}}}}{c^{2}} and that the viscosity contributions are of the same order. The fluid describes all the relevant physics at long scales k and permits a manifestly convergent perturbative expansion in the size of the matter perturbations δ( k) for all the observables. As an example, we calculate the correction to the power spectrum at order δ( k)^{4}. The predictions of the effective field theory are found to be in much better agreement with observation than standard cosmological perturbation theory, already reaching percent precision at this order up to a relatively short scale k ⋍ 0 .24 h Mpc^{1}.
 Publication:

Journal of High Energy Physics
 Pub Date:
 September 2012
 DOI:
 10.1007/JHEP09(2012)082
 arXiv:
 arXiv:1206.2926
 Bibcode:
 2012JHEP...09..082C
 Keywords:

 Cosmology of Theories beyond the SM;
 Stochastic Processes;
 Renormalization Regularization and Renormalons;
 Astrophysics  Cosmology and Extragalactic Astrophysics;
 General Relativity and Quantum Cosmology;
 High Energy Physics  Phenomenology;
 High Energy Physics  Theory
 EPrint:
 v2: typos corrected, JHEP published version