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arXiv · 2609.03012

Universal CMB Phase Coherence from Single-Field Inflation

Siméon Vareilles·Thomas Colas·Julien Grain·Federico Piazza·Vincent Vennin
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Abstract

The phase coherence of primordial perturbations shapes the acoustic peaks of the CMB and is regarded as a key signature of inflation. Inflationary scenarios at different energy scales, thus with different durations, are commonly expected to leave different levels of coherence. We show this expectation fails: because the curvature perturbation is conserved on super-Hubble scales, the coherence at recombination inherits a value fixed by the observed primordial spectrum alone. This holds irrespective of the inflationary energy scale and the subsequent expansion history.

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Siméon Vareilles, Thomas Colas, Julien Grain, Federico Piazza, Vincent Vennin. 2026-09-02. Universal CMB Phase Coherence from Single-Field Inflation. https://arxiv.org/abs/2609.03012

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