Post-inflationary enhancement of adiabatic perturbations in modular cosmology

2025/07/04 by Quaglia, Rodrigo Gonzalez, Michelotti, Martino, Roest, Diederik +3 · 2 citations
#Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences

paper · doi:10.48550/arxiv.2507.03610

Abstract

We show that multi-field inflationary models with negligible turning in field space during inflation can lead to an effective sourcing of adiabatic from entropic perturbations \it after the end of inflation. We illustrate this general phenomenon with a detailed analysis of an inflationary model whose scalar potential is determined by modular invariance. Its entropic perturbations are frozen during inflation, but instead, they are converted into adiabatic perturbations in the first post-inflationary e-folds. The curvature power spectrum, giving rise to CMB fluctuations, reaches a novel and enhanced plateau in this process; we address the implications for the inflationary observables A_s, n_s and r.

Citations

• Higgs-Modular Inflation
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Cited by

• Fibre Inflation Meets Quintessence: Implications of Perturbative Stabilisation
• Heavy Field Effects on Inflationary Models in Light of ACT Data

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• Adiabatic and entropy perturbations in cosmology
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• Non-Adiabatic Perturbations from Single-Field Inflation
• Cosmological Perturbations in an Inflationary Universe
• Models of inflation and the spectral index of the adiabatic density perturbation