Seven Lessons from Manyfield Inflation in Random Potentials

Abstract

We study inflation in models with many interacting fields subject to randomly generated scalar potentials. We use methods from non-equilibrium random matrix theory to construct the potentials and an adaption of the 'transport method' to evolve the two-point correlators during inflation. This construction allows, for the first time, for an explicit study of models with up to 100 interacting fields supporting a period of 'approximately saddle-point' inflation. We determine the statistical predictions for observables by generating over 30,000 models with 2-100 fields supporting at least 60 efolds of inflation. These studies lead us to seven lessons: i) Manyfield inflation is not single-field inflation, ii) The larger the number of fields, the simpler and sharper the predictions, iii) Planck compatibility is not rare, but future experiments may rule out this class of models, iv) The smoother the potentials, the sharper the predictions, v) Hyperparameters can transition from stiff to sloppy, vi) Despite tachyons, isocurvature can decay, vii) Eigenvalue repulsion drives the predictions. We conclude that many of the 'generic predictions' of single-field inflation can be emergent features of complex inflation models.

53 pages, 19 figures. Minor edits to v1

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• Pole N-flation
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• Curvature Perturbations From Stochastic Particle Production During Inflation
• Towards a complete mass spectrum of type-IIB flux vacua at large complex structure
• Stochastic Particle Production in a de Sitter Background
• (Slow-)Twisting inflationary attractors
• Inflation as an Information Bottleneck - A strategy for identifying universality classes and making robust predictions
• Many-field Inflation: Universality or Prior Dependence?
• Learning to Inflate
• Inhomogeneous Initial Data and Small-Field Inflation
• Non-Gaussianity in rapid-turn multi-field inflation
• Local, algebraic simplifications of Gaussian random fields
• Inflation in a Gaussian Random Landscape
• Non-Gaussianity after many-field reheating