A general proof of the conservation of the curvature perturbation
Abstract
Without invoking a perturbative expansion, we define the cosmological curvature perturbation, and consider its behaviour assuming that the universe is smooth over a sufficiently large comoving scale. The equations are simple, resembling closely the firstorder equations, and they lead to results which generalize those already proven in linear perturbation theory and (in part) in secondorder perturbation theory. In particular, the curvature perturbation is conserved provided that the pressure is a unique function of the energy density.
 Publication:

Journal of Cosmology and Astroparticle Physics
 Pub Date:
 May 2005
 DOI:
 10.1088/14757516/2005/05/004
 arXiv:
 arXiv:astroph/0411220
 Bibcode:
 2005JCAP...05..004L
 Keywords:

 Astrophysics;
 General Relativity and Quantum Cosmology;
 High Energy Physics  Phenomenology
 EPrint:
 9 pages, revtex4, no figures