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Seeding primordial black holes in multifield inflation

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arxiv 2004.06106 v3 pith:Y26MXPDT submitted 2020-04-13 astro-ph.CO gr-qchep-phhep-th

classification astro-ph.COgr-qchep-phhep-th
keywords zetalargeblackdeltaenhancementsholesinflationaryisocurvature
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abstract

The inflationary origin of primordial black holes (PBHs) relies on a large enhancement of the power spectrum $\Delta_\zeta$ of the curvature fluctuation $\zeta$ at wavelengths much shorter than those of the cosmic microwave background anisotropies. This is typically achieved in models where $\zeta$ evolves without interacting significantly with additional (isocurvature) scalar degrees of freedom. However, quantum gravity inspired models are characterized by moduli spaces with highly curved geometries and a large number of scalar fields that could vigorously interact with $\zeta$ (as in the cosmological collider picture). Here we show that isocurvature fluctuations can mix with $\zeta$ inducing large enhancements of its amplitude. This occurs whenever the inflationary trajectory experiences rapid turns in the field space of the model leading to amplifications that are exponentially sensitive to the total angle swept by the turn, which induce characteristic observable signatures on $\Delta_\zeta$. We derive accurate analytical predictions and show that the large enhancements required for PBHs demand non-canonical kinetic terms in the action of the multifield system.

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Cited by 6 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. 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.

  3. Are Primordial Black Holes Truly Fine-Tuned?

    astro-ph.CO 2025-12 conditional novelty 5.0 of 10

    Using a normalized sensitivity measure γ=c/c̄, the authors find γ≈1 for three single-field ultra-slow-roll inflation models and conclude PBH production is not technically unnatural.

  4. Implications for Pulsar Timing Arrays of Sub-solar Black Hole Detections: From LVK to Einstein Telescope and Cosmic Explorer

    astro-ph.CO 2025-08 conditional novelty 5.0 of 10

    A Bayesian analysis shows that a future sub-solar PBH detection would make the primordial SIGW interpretation of PTA data favored over the SMBH interpretation, but this preference is driven by the detection prior.

  5. Three-Field String Inflation with Perturbative Corrections: Dynamics and Implications

    hep-th 2025-02 conditional novelty 5.0 of 10

    A three-field inflation model is constructed in a perturbative large-volume string setup where loop and higher-derivative corrections stabilize the moduli and produce a two-stage inflationary trajectory.

  6. Cosmological constraints on small-scale primordial non-Gaussianity

    astro-ph.CO 2025-05 conditional novelty 4.0 of 10

    Current pulsar-timing, CMB, BAO and PBH data constrain the small-scale local f_NL to -10.0 < f_NL < 1.2 for a monochromatic primordial power spectrum, with that constraint conditional on the spectral amplitude A_zeta = 10^-2.

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