Gauge-invariant perturbations at second order in two-field inflation
Abstract
We study the second-order gauge-invariant adiabatic and isocurvature perturbations in terms of the scalar fields present during inflation, along with the related fully non-linear space gradient of these quantities. We discuss the relation with other perturbation quantities defined in the literature. We also construct the exact cubic action of the second-order perturbations (beyond any slow-roll or super-horizon approximations and including tensor perturbations), both in the uniform energy density gauge and the flat gauge in order to settle various gauge-related issues. We thus provide the tool to calculate the exact non-Gaussianity beyond slow-roll and at any scale.
Keywords
Cite
@article{arxiv.1111.5838,
title = {Gauge-invariant perturbations at second order in two-field inflation},
author = {Eleftheria Tzavara and Bartjan van Tent},
journal= {arXiv preprint arXiv:1111.5838},
year = {2012}
}
Comments
28 pages, no figures. v2: Added a summary subsection 4.3 with further discussion of the results. Generalized all super-horizon results of section 4 and appendix A to exact ones. Other minor textual changes and references added. Conclusions unchanged. Matches published version