Suppression of long-wavelength CMB spectrum from the no-boundary initial condition

TL;DR

This paper proposes that the long-wavelength suppression in the CMB spectrum can be explained by a massive inflaton field originating from the no-boundary initial condition, aligning with observed data.

Contribution

It introduces a model where a massive inflaton from the no-boundary wave function causes power suppression at large scales in the CMB spectrum.

Findings

Power spectrum is suppressed at long wavelengths with a moderately massive inflaton.

The model aligns with Planck data on large-scale CMB correlations.

The initial vacuum state is derived from a Euclidean instanton in a compact manifold.

Abstract

The lack of correlations at the long-wavelength scales of the cosmic microwave background spectrum is a long-standing puzzle and it persists in the latest Planck data. By considering the Hartle-Hawking no-boundary wave function as the initial condition of the inflationary universe, we propose that the power suppression can be the consequence of a massive inflaton, whose initial vacuum is the Euclidean instanton in a compact manifold. We calculate the primordial power spectrum of the perturbations, and find that as long as the scalar field is moderately massive, the power spectrum is suppressed at the long-wavelength scales.