{"paper":{"title":"Pushing the Primordial Frontier: Exact Linear Solutions in Multifield Inflation","license":"http://creativecommons.org/licenses/by/4.0/","headline":"","cross_cats":["hep-ph","hep-th"],"primary_cat":"astro-ph.CO","authors_text":"Claudio Mu\\~noz, Gonzalo A. Palma, Javier Huenupi, Spyros Sypsas","submitted_at":"2026-06-16T17:59:12Z","abstract_excerpt":"We present exact analytic solutions for the linear dynamics of a two-field inflationary system in which the primordial curvature perturbation $\\zeta$ is coupled to an isocurvature perturbation $\\sigma$ of entropy mass $\\mu$. The solutions are valid for arbitrary values of $\\mu$ and the dimensionless interaction strength $\\lambda$, within a quasi-de Sitter background. They therefore provide analytic control over the strongly coupled regime in which $\\zeta$ interacts with light isocurvature fields, commonly associated with rapid-turn inflation. As a first application, we derive the amplitude of "},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"2606.18248","kind":"arxiv","version":1},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/2606.18248/integrity.json","findings":[],"available":true,"detectors_run":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938"},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}