On backreaction effects in geometrical destabilisation of inflation

Abstract

We study the geometrical instability arising in multi-field models of inflation with negatively-curved field space. We analyse how the homogeneous background evolves in presence of geometrical destabilisation, and show that, in simple models, a kinematical backreaction effect takes place that shuts off the instability. We also follow the evolution of the unstable scalar fluctuations. We show that they assist the kinematical backreaction while remaining in the perturbative regime. We conclude that, in the simplest models of geometrical destabilisation, inflation does not end prematurely, but rather proceeds along a modified, sidetracked, field-space trajectory.

arXiv comment25 pages, 4 figures, matches the published version

References in corpus (22)

• Encyclopaedia Inflationaris
• A General Analytic Formula for the Spectral Index of the Density Perturbations produced during Inflation
• Adiabatic and entropy perturbations from inflation
• Supersymmetry Breaking in the Early Universe
• Planck 2015 results. XVII. Constraints on primordial non-Gaussianity
• Scalar perturbations during multiple-field slow-roll inflation
• The Gelaton Scenario: Equilateral non-Gaussianity from multi-field dynamics
• Curvature and isocurvature perturbations in two-field inflation
• Adiabatic and Isocurvature Perturbations for Multifield Generalized Einstein Models
• Cosmological perturbations from multi-field inflation in generalized Einstein theories
• Beginning inflation in an inhomogeneous universe
• Geometrical Destabilization of Inflation
• Primordial fluctuations and non-Gaussianities in sidetracked inflation
• The stochastic spectator
• The hybrid inflation waterfall and the primordial curvature perturbation
• Density Perturbations in Multifield Inflationary Models
• Slow-roll Inflation for Generalized Two-Field Lagrangians
• On reaching the adiabatic limit in multi-field inflation
• Geometrical destabilization, premature end of inflation and Bayesian model selection
• Contribution of the hybrid inflation waterfall to the primordial curvature perturbation
• Inflationary stochastic anomalies
• A geometrical instability for ultra-light fields during inflation?

Cited by in corpus (16)

• Scaling attractors in multi-field inflation
• Revisiting small-scale fluctuations in $\alpha$-attractor models of inflation
• Hyper non-Gaussianities in inflation with strongly non-geodesic motion
• The rapid-turn inflationary attractor
• A manifestly covariant theory of multifield stochastic inflation in phase space: solving the discretisation ambiguity in stochastic inflation
• Revisiting non-Gaussianity in multifield inflation with curved field space
• On the inflationary massive field with a curved field manifold
• Attractors, Bifurcations and Curvature in Multi-field Inflation
• Mild Non-Gaussianities under Perturbative Control from Rapid-Turn Inflation Models
• Higgs vacuum (in)stability during inflation: the dangerous relevance of de Sitter departure and Planck-suppressed operators
• Multi-field Inflation in High-Slope Potentials
• Geometrical Destabilisation of Ultra-Light Axions in String Inflation
• Large and small field inflation from hyperbolic sigma models
• Non-Gaussianity in rapid-turn multi-field inflation
• Anatomy of geometrical destabilization of inflation
• On the F-term problem and quintessence supersymmetry breaking