Largescale curvature perturbations with spatial and time variations of the inflaton decay rate
Abstract
We present a gaugeinvariant formalism to study the evolution of the curvature and entropy perturbations in the case in which spatial and time variations of the inflaton decay rate into ordinary matter are present. During the reheating stage after inflation, curvature perturbations can vary with time on superhorizon scales sourced by a gaugeinvariant inflaton decay rate perturbation. We show that the latter is a function not only of the spatial variations of the decay rate generated during inflation, as envisaged in a recently proposed scenario, but also of the time variation of the inflaton decay rate during reheating. If only the second source is present, the final curvature perturbation at the end of the reheating stage is proportional to the curvature perturbation at the beginning of reheating, with a coefficient of proportionality which can be either smaller or larger than unity depending upon the underlying physics governing the time variation of the inflaton decay rate. As a consequence, we show that the standard consistency relation between the amplitude of curvature perturbations, the amplitude of tensor perturbations and the tensor spectral index of onesinglefield models of inflation is violated and there is the possibility that the tensortocurvature amplitude ratio is larger than in the standard case.
 Publication:

Journal of Cosmology and Astroparticle Physics
 Pub Date:
 August 2003
 DOI:
 10.1088/14757516/2003/08/007
 arXiv:
 arXiv:astroph/0306416
 Bibcode:
 2003JCAP...08..007M
 Keywords:

 Astrophysics;
 High Energy Physics  Phenomenology;
 High Energy Physics  Theory
 EPrint:
 LaTeX file, 21 pages. A few typos corrected