Large-scale Perturbations from the Waterfall Field in Hybrid Inflation

Abstract

We estimate large-scale curvature perturbations from isocurvature fluctuations in the waterfall field during hybrid inflation, in addition to the usual inflaton field perturbations. The tachyonic instability at the end of inflation leads to an explosive growth of super-Hubble scale perturbations, but they retain the steep blue spectrum characteristic of vacuum fluctuations in a massive field during inflation. The power spectrum thus peaks around the Hubble-horizon scale at the end of inflation. We extend the usual delta-N formalism to include the essential role of these small fluctuations when estimating the large-scale curvature perturbation. The resulting curvature perturbation due to fluctuations in the waterfall field is second-order and the spectrum is expected to be of order 10^{-54} on cosmological scales.

10 pages, 4 figures; v2 comments added on application of delta-N formalism including Hubble scale fluctuations

References in corpus (6)

• Particle physics models of inflation and curvaton scenarios
• Nongaussianity from Tachyonic Preheating in Hybrid Inflation
• No Large Scale Curvature Perturbations during Waterfall of Hybrid Inflation
• Analytical Study of Mode Coupling in Hybrid Inflation
• Non-Gaussianity constrains hybrid inflation
• Curvature perturbation spectrum from false vacuum inflation

Cited by in corpus (31)

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• Purely quadratic non-Gaussianity from tachyonic instability: Primordial black holes and scalar-induced gravitational waves