Suppression of the long-wavelength CMB spectrum from the Hartle–Hawking wave function in the Starobinsky-type inflation model

Journal Article · 12 December 2019 · Physics of the Dark Universe

DOI: https://doi.org/10.1016/j.dark.2019.100435 · OSTI ID:1608984

Chen, Pisin ^[1]; Yeh, Hsiao-Heng ^[2]; Yeom, Dong-Han ^[3]

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1. National Taiwan Univ., Taipei (Taiwan); SLAC National Accelerator Lab., Menlo Park, CA (United States). Kavli Institute for Particle Astrophysics and Cosmology
2. National Taiwan Univ., Taipei (Taiwan)
3. Asia Pacific Center for Theoretical Physics, Pohang (Republic of Korea); POSTECH, Pohang (Republic of Korea); Pusan National Univ., Busan (Republic of Korea)

The lack of correlations on the large scale cosmic microwave background (CMB) anisotropy provides a potential window to probe beyond the standard inflationary scenario. Herein, we investigate the primordial power spectrum based on the Hartle–Hawking (HH) no-boundary proposal for a homogeneous, isotropic, and spatially-closed universe that leads to Starobinsky-type inflation after the classicalization. While we found that there is no suppression at large scales in the standard $R+R^2$ theory, we also found that it is possible to sufficiently suppress the large-scale power spectrum if a pre-inflationary stage is introduced to the Starobinsky-type model. In addition, such a pre-inflationary stage will be helpful to explain the preference of large e-foldings of the $HH$ proposal. We calculate the $$C^{TT}_{ℓ}$$ correlation function and show that our proposal gives a better fit to the Planck CMB data. This suggests that our universe might have begun with a compact $HH$ state with a small positive curvature.

• Research Organization: SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
• Sponsoring Organization: USDOE; Taiwan National Science Council; Korean Ministry of Education, Science and Technology; National Research Foundation of Korea (NRF); Asia Pacific Center for Theoretical Physics
• Grant/Contract Number: AC02-76SF00515; 2018R1D1A1B07049126
• OSTI ID: 1608984
• Alternate ID(s): OSTI ID: 1579446
• Journal Information: Physics of the Dark Universe, Vol. 27, Issue C; ISSN 2212-6864
• Publisher: ElsevierCopyright Statement
• Country of Publication: United States
• Language: English