http://arxiv.org/abs/1404.2985
We study the effects of a general class of features of the inflaton potential on the spectrum and bispectrum of primordial curvature perturbations. These features correspond to a discontinuity in the $n-th$ order derivative of the potential which is dumped exponentially away from the value of the field where the feature happens. We provide fully numerical calculations and analytical approximations for the spectrum and the bispectrum, which are in good agreement with each other.
The spectrum of primordial perturbations has oscillations around the scale $k_0$ which leaves the horizon at the time $\tau_0$ when the feature occurs, with amplitude and phase of the oscillations are determined by the size and the order of the discontinuity. Both in the squeezed and equilateral large scale limit the bispectrum has an oscillatory behavior whose phase depends on the parameters determining the discontinuity, and whose amplitude is inversely proportional to the scale. The small scale bispectrum in the squeezed and equilateral limits have a very similar form and are quadratically suppressed. Given the generality of the class of features we study this could be used to classify and model phenomenologically different types of non gaussian features encountered in observational data such as $CMB$ or large scale structure.
A. Romano and A. Cadavid
Mon, 14 Apr 14
36/41