Eur. Phys. J. C (2018) 78: 930
https://doi.org/10.1140/epjc/s10052-018-6426-4

Regular Article - Theoretical Physics

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

¹ Department of Physics, National Taiwan University, Taipei, 10617, Taiwan
² Leung Center for Cosmology and Particle Astrophysics, National Taiwan University, Taipei, 10617, Taiwan
³ SLAC National Accelerator Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, CA, 94305, USA
⁴ Graduate Institute of Astrophysics, National Taiwan University, Taipei, 10617, Taiwan
⁵ The Asia Pacific Center for Theoretical Physics, Pohang, 37673, South Korea
⁶ Department of Physics, POSTECH, Pohang, 37673, South Korea

^* e-mail: innocent.yeom@gmail.com

Received: 16 July 2018
Accepted: 6 November 2018
Published online: 14 November 2018

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.