http://arxiv.org/abs/1508.05687
We study the effects of a class of features of the potential of slow-roll inflationary models corresponding to a step symmetrically dumped by an even power negative exponential factor. We compute the effects on the background evolution and on the scalar and tensor perturbations. This class of features differs from other branch-type features considered previously because the potential is only affected in a limited range of the scalar field value, and is symmetric respect to the location of the feature. As a consequence this type of features only affects the spectrum and bispectrum in a narrow range of scales which leave the horizon during the time interval corresponding to the modification of the potential, contrary to branch-type features which have effects on all the perturbation modes leaving the horizon when the field value is within the interval defining the branch.
When the scalar field enters the range affected by the feature the slow-roll conditions are temporarily violated, but once the field leaves the interval affected by the feature the slow roll regime is re-established. The tensor-to-scalar ration, the spectrum and bispectrum of primordial curvature perturbations are affected by oscillations around the scale $k_0$ exiting the horizon at the time $\tau_0$ of the feature. The amplitude of the oscillations depends on the parameters defining the feature, and the effects are larger when the potential has a steeper change, since in this case the slow-roll violation is also stronger. Due to the local nature of their effects these type of features could be used to model local glitches of the power spectrum without affecting other scales.
A. Cadavid and A. Romano
Tue, 25 Aug 15
6/69
Comments: 15 pages, 12 figures