Primordial Curvature Fluctuation and Its Non-Gaussianity in Models with Modulated Reheating
Jul, 2008
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Abstract: (arXiv)
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 non-linearity parameters and 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 pre-existing adiabatic perturbations produced from the inflaton fluctuations. It has been known that the non-linearity between the curvature perturbations and the fluctuations of the decay rate can yield non-Gaussianity at the level of , but we find that the non-linearity 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 non-linearity 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 but with a different sign of . This provides a possibility to discriminate these two competitive models by looking at the sign of . 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.- 98.80.Cq
- reheating
- perturbation: adiabatic
- power spectrum: primordial
- inflaton: fluctuation
- curvature: perturbation
- non-Gaussianity
- curvaton
- inflaton: decay rate
- inflation: chaos
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