2026/06/16 by Javier Huenupi, Claudio Muñoz, Gonzalo A. Palma +1 · 2 citations
#astro-ph.CO #hep-ph #hep-th
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, within a quasi-de Sitter background. 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.