Primordial curvature fluctuation and its non-Gaussianity in models with modulated reheating

Journal Article · Mon Sep 15 04:00:00 EDT 2008 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.78.063545· OSTI ID:21250853

Ichikawa, Kazuhide ^[1]; Suyama, Teruaki ^[2]; Takahashi, Tomo ^[3]; Yamaguchi, Masahide ^[4]

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1. Department of Physics and Astronomy, University College London, London WC1E 6BT (United Kingdom)
2. Institute for Cosmic Ray Research, University of Tokyo, Kashiwa 277-8582 (Japan)
3. Department of Physics, Saga University, Saga 840-8502 (Japan)
4. Department of Physics and Mathematics, Aoyama Gakuin University, Sagamihara 229-8558 (Japan)

We investigate non-Gaussianity in the modulated reheating scenario where fluctuations of the decay rate of the inflaton generate adiabatic perturbations, paying particular attention to the nonlinearity (NL) parameters f{sub NL}, {tau}{sub NL}, and g{sub NL} as well as the scalar spectral index and tensor-to-scalar ratio which characterize the nature of the primordial power spectrum. We also take into account the preexisting adiabatic perturbations produced from the inflaton fluctuations. It has been known that the nonlinearity between the curvature perturbations and the fluctuations of the decay rate can yield non-Gaussianity at the level of f{sub NL}{approx}O(1), but we find that the nonlinearity between the decay rate and the modulus field which determines the decay rate can generate much greater non-Gaussianity. We also discuss a consistency relation among nonlinearity parameters which holds in the scenario and find that the modulated reheating yields a different one from that of the curvaton model. In particular, they both can yield a large positive f{sub NL} but with a different sign of g{sub NL}. This provides a possibility to discriminate these two competitive models by looking at the sign of g{sub NL}. Furthermore, we work on some concrete inflation models and investigate in what cases models predict the spectral index and the tensor-to-scalar ratio allowed by the current data while generating large non-Gaussianity, which may have many implications for model buildings of the inflationary universe.

• OSTI ID: 21250853
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 6 Vol. 78; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ADIABATIC PROCESSES
DISTURBANCES
FLUCTUATIONS
INFLATION
INFLATIONARY UNIVERSE
NONLINEAR PROBLEMS
PERTURBATION THEORY
SPECTRA