Pushing the Primordial Frontier: Exact Linear Solutions in Multifield Inflation
Abstract
We present exact analytic solutions for the linear dynamics of a two-field inflationary system in which the primordial curvature perturbation ζ is coupled to an isocurvature perturbation σ of entropy mass μ. The solutions are valid for arbitrary values of μ and the dimensionless interaction strength λ. They therefore provide analytic control over the strong mixing regime in which ζ interacts with light isocurvature fields, commonly associated with rapid-turn inflation. As a first application, we derive the amplitude of the primordial power spectrum in closed form, obtaining an expression that interpolates between the weakly mixed, strongly mixed, light-field, and heavy-field regimes. These results open the way to analytic studies of multifield observables beyond the power spectrum, including non-Gaussianity, particle production, and loop corrections.
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BibTeX
@misc{huenupi2026pushing,
title = {{Pushing the Primordial Frontier: Exact Linear Solutions in Multifield Inflation}},
author = {Javier Huenupi and Claudio Muñoz and Gonzalo A. Palma and Spyros Sypsas},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2606.18248},
eprint = {2606.18248},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.18248},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Pushing the Primordial Frontier: Exact Linear Solutions in Multifield Inflation
AU - Javier Huenupi
AU - Claudio Muñoz
AU - Gonzalo A. Palma
AU - Spyros Sypsas
PY - 2026
DA - 2026/10/27
PB - arXiv
DO - 10.48550/arxiv.2606.18248
UR - https://arxiv.org/abs/2606.18248
AB - We present exact analytic solutions for the linear dynamics of a two-field inflationary system in which the primordial curvature perturbation ζ is coupled to an isocurvature perturbation σ of entropy mass μ. The solutions are valid for arbitrary values of μ and the dimensionless interaction strength λ. They therefore provide analytic control over the strong mixing regime in which ζ interacts with light isocurvature fields, commonly associated with rapid-turn inflation. As a first application, we derive the amplitude of the primordial power spectrum in closed form, obtaining an expression that interpolates between the weakly mixed, strongly mixed, light-field, and heavy-field regimes. These results open the way to analytic studies of multifield observables beyond the power spectrum, including non-Gaussianity, particle production, and loop corrections.
ER -