Fine Features in the Primordial Power Spectrum

TL;DR

This paper investigates whether modifications in the inflaton potential during inflation can explain the observed dip and bump in the primordial power spectrum, concluding that such features are unlikely to be generated by potential features due to amplitude constraints.

Contribution

It provides an analytic evaluation of how inflaton potential features affect the primordial power spectrum and demonstrates the difficulty in reproducing observed anomalies.

Findings

Adding features to the inflaton potential cannot produce the observed dip and bump with sufficient amplitude.

The relation between inflaton potential shape and power spectrum features is constrained by slow-roll corrections.

Fine-tuning the potential shape results in too small amplitude of the spectral features.

Abstract

A possible origin of the anomalous dip and bump in the primordial power spectrum, which are reconstructed from WMAP data corresponding to the multipole $\ell=100\sim 140$ by using the inversion method, is investigated as a consequence of modification of scalar field dynamics in the inflation era. Utilizing an analytic formula to handle higher order corrections to the slow-roll approximation, we evaluate the relation between a detailed shape of inflaton potential and a fine structure in the primordial power spectrum. We conclude that it is unlikely to generate the observed dip and bump in the power spectrum by adding any features in the inflaton potential. Though we can make a fine enough shape in the power spectrum by controlling the feature of the potential, the amplitude of the dip and bump becomes too small in that case.