TY - JOUR

T1 - A truncated primordial power spectrum and its impact on B-mode polarization

AU - Liu, Jingwei

AU - Melia, Fulvio

N1 - Publisher Copyright:
© 2024 The Author(s)

PY - 2024/6

Y1 - 2024/6

N2 - 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 CℓBB 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.

AB - 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 CℓBB 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.

KW - B-mode polarization

KW - Cosmic microwave background

KW - Cosmology

KW - Inflation

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U2 - 10.1016/j.physletb.2024.138645

DO - 10.1016/j.physletb.2024.138645

M3 - Article

AN - SCOPUS:85190880161

SN - 0370-2693

VL - 853

JO - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

JF - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

M1 - 138645

ER -