Scale dependence of local fNL

Chris Byrnes, S. Nurmi, Gianmassimo Tasinato, David Wands

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We consider possible scale-dependence of the non-linearity parameter fNL in local and quasi-local models of non-Gaussian primordial density perturbations. In the simplest model where the primordial perturbations are a quadratic local function of a single Gaussian field then fNL is scale-independent by construction. However scale-dependence can arise due to either a local function of more than one Gaussian field, or due to non-linear evolution of modes after horizon-exit during inflation. We show that the scale dependence of fNL is typically first order in slow-roll. For some models this may be observable with experiments such as Planck provided that fNL is close to the current observational bounds.
Original languageEnglish
JournalJournal of Cosmology and Astroparticle Physics
Issue number2
Publication statusPublished - 2010


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