Carving out the Multifield Cosmological Collider Landscape

arXiv:2609.37570 · astro-ph.CO, gr-qc, hep-ph, hep-th · Submitted 2026-09-29 · Read on arXiv

astro-ph.CO, gr-qc, hep-ph, hep-th

Submitted: 2026-09-29

Updated: 2026-09-29

Comments: 6 pages without appendices, 8 figures, 3 tables

License: http://creativecommons.org/licenses/by/4.0/

The gist: We show that inflation with a large number of fields, as predicted by concrete ultraviolet embeddings, generically produces almost-local cosmological collider signals in the bispectrum squeezed limit.

Terminology

Abstract

We show that inflation with a large number of fields, as predicted by concrete ultraviolet embeddings, generically produces almost-local cosmological collider signals in the bispectrum squeezed limit. We construct the most general boost-breaking mixings between the curvature perturbation and N f additional fields, and extract the late-time scaling dimensions that dictate the soft limits of cosmological correlators. For a handful of fields, an enhanced squeezed limit (with potential oscillations) is a fine-tuned signal. At large N f about100, however, mixings generically drive the scaling dimensions toward the unitarity boundary. We show that this is a direct consequence of extreme value statistics and random-matrix universality, turning an almost-local bispectrum shape into a generic prediction for almost any masses and mixings.

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