Local non-Gaussianity from rapidly varying sound speeds
Abstract
We study the effect of non-trivial sound speeds on local-type non-Gaussianity during multiple-field inflation. To this end, we consider a model of multiple-field DBI and use the deltaN formalism to track the super-horizon evolution of perturbations. By adopting a sum separable Hubble parameter we derive analytic expressions for the relevant quantities in the two-field case, valid beyond slow variation. We find that non-trivial sound speeds can, in principle, curve the trajectory in such a way that significant local-type non-Gaussianity is produced. Deviations from slow variation, such as rapidly varying sound speeds, enhance this effect. To illustrate our results we consider two-field inflation in the tip regions of two warped throats and find large local-type non-Gaussianity produced towards the end of the inflationary process.
Cite
@article{arxiv.1203.6625,
title = {Local non-Gaussianity from rapidly varying sound speeds},
author = {Jon Emery and Gianmassimo Tasinato and David Wands},
journal= {arXiv preprint arXiv:1203.6625},
year = {2012}
}
Comments
30 pages, 7 figures; typos corrected, references added, accepted for publication in JCAP