Inflation in string-inspired cosmology and suppression of CMB low multipoles

TL;DR

This paper proposes a string-inspired cosmological model where a modulus-driven phase suppresses low multipoles in the CMB power spectrum, linking extra dimensions to observable anisotropies.

Contribution

It introduces a nonsingular inflationary scenario with a pre-inflationary modulus-driven phase that explains low multipole suppression in the CMB.

Findings

Suppressed power spectrum at low multipoles due to modulus-driven phase

Model achieves sufficient e-foldings and scale-invariant perturbations

Potential observational signatures of extra dimensions in CMB anisotropies

Abstract

We construct a string-inspired nonsingular cosmological scenario in which an inflaton field is driven up the potential before the graceful exit by employing a low-energy string effective action with an orbifold compactification. This sets up an initial condition for the inflaton to lead to a sufficient amount of $e$-foldings and to generate a nearly scale-invariant primordial density perturbation during slow-roll inflation. Our scenario provides an interesting possibility to explain a suppressed power spectrum at low multipoles due to the presence of the modulus-driven phase prior to slow-roll inflation and thus can leave a strong imprint of extra dimensions in observed CMB anisotropies.