What question did this study set out to answer?

To document a parameter-free prediction of the BRISM framework for the CMB temperature spectrum.

March 14, 2026Open Access

B11: BRISM ε = 1/π² and the CMB Low‑ℓ Power Deficit: A Parameter‑Free Structural Prediction

Key Points

To document a parameter-free prediction of the BRISM framework for the CMB temperature spectrum.
Analyzed the CMB under the BRISM framework with ε = 1/π².
Observed low-multipole behavior through predictions for multipoles ℓ = 2 and ℓ = 30.
Utilized Planck 2018 Commander data for comparison.
Predicted ≈ −9.5% deficit at ℓ = 2 and ≈ −5.1% at ℓ = 30.
Observed residuals matched predictions in amplitude and taper.
Results indicate structural agreement without adjustable parameters.

Abstract

This technical note documents a parameter‑free prediction of the BRISM (BRane Interface Substrate Model) framework for the Cosmic Microwave Background (CMB) temperature spectrum at large angular scales. Under phase neutrality, positivity, σ‑additivity, and two‑sided Naimark–Stinespring completeness, BRISM fixes a universal interface scale ε = 1/π², which induces a smooth infrared suppression envelope. Applied to the CMB, this leads to a specific low‑multipole modulation of the form Δℓ = −ε / (1 + ℓ/π³), predicting a ≈ −9.5% deficit at ℓ = 2 and ≈ −5.1% at ℓ = 30, with rapid decay for higher multipoles. Digitized Planck 2018 Commander residuals (ℓ = 2…30) exhibit matching amplitude, localization, and taper, indicating a structural agreement without adjustable parameters. The purpose of this note is to timestamp this prediction for later comparison with full CMB likelihood analyses; no refitting of ΛCDM parameters is performed here.All BRISM papers on Zenodo >> Searchlist

B11: BRISM ε = 1/π² and the CMB Low‑ℓ Power Deficit: A Parameter‑Free Structural Prediction

Key Points

Abstract

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