Primordial non-Gaussianity from mixed inflaton-curvaton perturbations

Jose Fonseca, David Wands

Research output: Contribution to journalArticlepeer-review


We characterise the primordial perturbations produced due to both inflaton and curvaton fluctuations in models where the curvaton has a quadratic, cosine or hyperbolic potential, and the inflaton potential is characterised by the usual slow-roll parameters. Isocurvature curvaton field perturbations can produce significant non-Gaussianity in the primordial density field, in contrast with adiabatic inflaton field perturbations which produce negligible non-Gaussianity for canonical scalar fields. A non-self-interacting curvaton with quadratic potential produces a local-type non-Gaussianity that is well described by the non-linearity parameter fNL, which may be scale-dependent when the inflaton perturbations dominate the power spectrum. We show how observational bounds on non-linearity parameters and the tensor-scalar ratio can be used to constrain curvaton and inflaton parameters. We find a consistency relation between the bispectrum and trispectrum parameters in a mixed inflaton-curvaton model for a quadratic curvaton potential. Self-interaction terms in the curvaton potential can lead to both a large trispectrum parameter, gNL, and scale-dependence of the non-linearity parameters.
Original languageEnglish
Article number028
Pages (from-to)028
JournalJournal of Cosmology and Astroparticle Physics
Issue number6
Early online date14 Jun 2012
Publication statusPublished - Jun 2012


  • inflation
  • physics of the early universe
  • cosmological perturbation theory


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