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Correlating features in the primordial spectra

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arxiv 1211.5619 v2 pith:EIRMFBGP submitted 2012-11-23 astro-ph.CO hep-th

classification astro-ph.COhep-th
keywords featuresbispectrumsoundspeedtheoryadiabaticbackgroundchange
verification ladder T0 review T1 audit T2 compute T3 formal
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Heavy fields coupled to the inflaton reduce the speed of sound in the effective theory of the adiabatic mode each time the background inflationary trajectory deviates from a geodesic. This can result in features in the primordial spectra. We compute the corresponding bispectrum and show that if a varying speed of sound induces features in the power spectrum, the change in the bispectrum is given by a simple formula involving the change in the power spectrum and its derivatives. In this manner, we provide a uniquely discriminable signature of a varying sound speed for the adiabatic mode during inflation that indicates the influence of heavy fields. We find that features in the bispectrum peak in the equilateral limit and, in particular, in the squeezed limit we find considerable enhancement entirely consistent with the single field consistency relation. From the perspective of the underlying effective theory, our results generalize to a wide variety of inflationary models where features are sourced by the time variation of background quantities. A positive detection of such correlated features would be unambiguous proof of the inflaton's nature as a single light scalar degree of freedom embedded in a theory that is UV completable.

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Cited by 7 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

  1. Pushing the Primordial Frontier: Exact Linear Solutions in Multifield Inflation

    astro-ph.CO 2026-06 unverdicted novelty 8.0 of 10

    Exact analytic solutions for coupled linear perturbations in two-field inflation provide a closed-form primordial power spectrum that interpolates weak, strong, light, and heavy field regimes.

  2. Dissecting the Scalar Cosmological Collider with the Cosmic Microwave Background

    astro-ph.CO 2026-07 accept novelty 7.0 of 10

    A joint Bayesian fit of the multi-field inflationary Lagrangian to Planck bispectrum data finds no cosmological collider signal (max Δχ²=5.3) and shows weak-mixing template searches are invalid except at the smallest masses.

  3. Pushing the Primordial Frontier: Cosmological Collider Signatures at Strong Mixing

    astro-ph.CO 2026-07 conditional novelty 7.0 of 10

    Exact analytic squeezed-limit bispectra for strongly mixed two-field inflation, nonperturbative in the curvature-isocurvature mixing λ.

  4. Searching for Inflationary Physics with the CMB Trispectrum: 1. Primordial Theory & Optimal Estimators

    astro-ph.CO 2025-02 conditional novelty 7.0 of 10

    A set of quasi-optimal CMB trispectrum estimators is derived for local, EFT, direction-dependent, spinning-particle, point-source, and lensing templates, enabling first collider searches.

  5. (The) Wiggles going non-linear

    astro-ph.CO 2026-05 unverdicted novelty 6.0 of 10

    N-body simulations calibrate a one-parameter damping model that predicts the non-linear matter power spectrum from wiggly primordial spectra to sub-percent accuracy when wiggle frequency is high enough.

  6. Primordial Sharp Features through the Nonlinear Regime of Structure Formation

    astro-ph.CO 2025-02 conditional novelty 6.0 of 10

    Sharp primordial features survive nonlinear structure formation as localised bumps or dips in the matter power spectrum, while their oscillatory patterns are erased, leaving an oscillatory imprint in the halo mass function.

  7. Penumbral Inflation from Calabi-Yau Boundaries

    hep-ph 2026-07 conditional novelty 5.0 of 10

    A string-theoretic construction maps Calabi-Yau boundary data into a logarithmic plateau inflation model, yielding the leading tensor-to-scalar prediction r = 4d/(q²N²) with Hodge degree d.

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