A truncated primordial power spectrum and its impact on B-mode polarization

Jingwei Liu, Fulvio Melia

Research output: Contribution to journalArticlepeer-review

Abstract

The absence of large-angle correlations in the temperature of the cosmic microwave background (CMB), confirmed by three independent satellite missions, creates significant tension with the standard model of cosmology. Previous work has shown, however, that a truncation, kmin, of the primordial power spectrum comprehensively resolves the anomaly and the missing power at ℓ≲5 (the low multipoles). Since this cutoff is consistent with the hypothesized delay of inflation well beyond the Planck time, we are strongly motivated to consider its possible impact on other observational signatures. In this Letter, we analyze and predict its influence on the most revealing probe awaiting measurement by upcoming missions—the B-mode polarization of the CMB, whose accurate determination should greatly impact the inflationary picture. We highlight the quantitative power of this discriminant by specifically considering the LiteBIRD mission, predicting the effect of kmin on both the angular power spectrum and the angular correlation function of the B-mode, for a range of tensor-to-scalar ratios, r. While its impact on the latter appears to be negligible, kmin should have a very pronounced effect on the former. We show that for r=0.036, kmin's impact on CBB at low ℓ's should be easily detectable by LiteBIRD, but will be largely hidden by the total uncertainty of the measurement if r≲0.02.

Original languageEnglish (US)
Article number138645
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Volume853
DOIs
StatePublished - Jun 2024

Keywords

  • B-mode polarization
  • Cosmic microwave background
  • Cosmology
  • Inflation

ASJC Scopus subject areas

  • Nuclear and High Energy Physics

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