Running spectral index from shooting-star moduli

Abstract

We construct an inflationary model that is consistent with both large non-Gaussianity and a running spectral index. The scenario of modulated inflation suggests that modulated perturbation can induce the curvature perturbation with a large non-Gaussianity, even if the inflaton perturbation is negligible. Using this idea, we consider a multi-field extension of the modulated inflation scenario and examine the specific situation where different moduli are responsible for the perturbation at different scales. We suppose that the additional moduli (shooting-star moduli) is responsible for the curvature perturbation at the earlier inflationary epoch and it generates the fluctuation with n>1 spectral index at this scale. After a while, another moduli (or inflaton) takes the place and generates the perturbation with n<1. At the transition point the two fluctuations are comparable with each other. We show how the spectral index is affected by the transition induced by the shooting-star moduli.

14 pages, latex, accepted for publication in JHEP

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• Delta-N formalism for the evolution of the curvature perturbations in generalized multi-field inflation
• Remote Inflation: Hybrid-like inflation without hybrid-type potential
• Ambiguity in running spectral index with an extra light field during inflation
• Non-standard kinetic term as a natural source of non-Gaussianity
• Evolution of curvature perturbation in generalized gravity theories
• Remote Inflation as hybrid-like sneutrino/MSSM inflation
• Curvatons and inhomogeneous scenarios with deviation from slow-roll
• Reconstruction of the isocurvaton scenario
• Modulated Inflation (@SUSY08)