What does this research mean for the field?

The lack of power at low multipoles in the Cosmic Microwave Background is a strict physical truncation caused by the universe emerging from a finite Euclidean instanton bounce at the QCD density scale, which also predicts a strict null tensor-to-scalar ratio (r=0). Novelty: ClaimNovelty.CONTRADICTORY. Consensus alignment: ConsensusAlignment.CHALLENGES_CONSENSUS.

What question did this study set out to answer?

This work aims to explain the low power at low multipoles in the CMB spectrum as a physical truncation.

May 20, 2026Open Access

Geometric Truncation of Low-Multipole CMB Power and Null B-Mode Prediction from a QCD-Scale Euclidean Instanton Bounce

Key Points

This work aims to explain the low power at low multipoles in the CMB spectrum as a physical truncation.
Utilized the Null-Vector Gravity (NVG) framework to derive the radius of the Genesis instanton.
Computed the e-folds required for cosmic expansion without relying on standard inflation models.
Defined the constraints on primordial perturbations based on the size of the instanton.
Calculated the radius of the Genesis instanton as 1.13 km and the required e-folds as approximately 53.2.
Predicted a strict suppression of the quadrupole (ℓ=2) and octupole (ℓ=3) in the CMB spectrum.
Established a null prediction for the tensor-to-scalar ratio r = 0, offering a testable target for B-mode experiments.

Abstract

The persistent lack of power at low multipoles (ℓ < 10) in the Cosmic Microwave Background (CMB) temperature anisotropy spectrum is traditionally dismissed as cosmic variance within the standard ΛCDM cosmological model. We propose that this anomaly is not a statistical fluctuation, but a strict physical truncation resulting from the universe emerging from a finite Euclidean instanton bounce at the Quantum Chromodynamics (QCD) density scale ρc ~ 10⁴ MeV/fm³, rather than from a point-like Big Bang singularity. Using the Null-Vector Gravity (NVG) framework, we analytically derive the radius of this Genesis instanton rc = 1. 13 km and the exact required number of e-folds Nₑ = ln (R₇䃐/rc) ≈ 53. 2, bypassing the arbitrary initial conditions and scalar fields of standard inflation. The maximum comoving wavelength of primordial perturbations is strictly bounded by the physical size of the instanton, resulting in an exact mathematical suppression of the quadrupole (ℓ=2) and octupole (ℓ=3). Furthermore, because the bounce occurs at an energy scale 10⁷⁷ times lower than the Planck scale, primordial tensor perturbations are not excited, resulting in a strict null prediction for the tensor-to-scalar ratio r = 0. This provides a definitive, falsifiable target for next-generation B-mode observatories such as LiteBIRD.

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