Non-Gaussianity and constraints for the variance of perturbations in the curvaton model

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dc.creatorValiviita, Jussi
dc.creatorSasaki, Misao
dc.creatorWands, David
dc.date2006-09-29
dc.date.accessioned2026-07-07T07:26:48Z
dc.date.available2026-07-07T07:26:48Z
dc.descriptionRecently, the primordial non-Gaussianity in the curvaton model has been predicted assuming sudden decay of the curvaton. We extend the calculation to non-instantaneous decay by employing delta N -formalism. The difference between the sudden-decay approximation and our numerical result is larger than 1% only if the non-linearity parameter is small, -1.16 < f_NL < 60. Thus it is safe to use the sudden-decay approximation when deriving constraints for the curvaton model from WMAP3 (f_NL < 114), but with the Planck forecast |f_NL| <5 one should employ the fully numerical result. Often, the curvaton perturbations $δσ$ have been assumed to be small compared to the background value of the curvaton field $σ_0$. Consequently, the variance $Δ^2 = <δσ^2> / σ_0^2$ has been assumed to be negligible. However, the measurements of CMB or large-scale structure perturbation amplitude do not constrain the variance if the main contribution to it comes from the ultraviolet (UV) scales, i.e., from smaller than observable scales. We discuss how, even in this case, observational constraints on non-Gaussianity set an upper bound to the small scale variance, Delta^2_UV < 90.
dc.description5 pages, 2 figures
dc.identifierhttps://arxiv.org/abs/astro-ph/0610001
dc.identifierhttp://arxiv.org/abs/astro-ph/0610001
dc.identifierContribution to the proceedings of the 40th Rencontres de Moriond, "Contents and structures of the universe", 2006
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/117160
dc.subjectAstrophysics
dc.subjectHigh Energy Physics - Phenomenology
dc.titleNon-Gaussianity and constraints for the variance of perturbations in the curvaton model
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