Non-Gaussianity from step features in the inflationary potential

Peter Adshead, Cora Dvorkin, Wayne Hu, Eugene A. Lim

Research output: Contribution to journalArticlepeer-review


We provide analytic solutions for the power spectrum and bispectrum of curvature fluctuations produced by a step feature in the inflaton potential, valid in the limit that the step is short and sharp. In this limit, the bispectrum is strongly scale dependent and its effective nonlinearity attains a large oscillatory amplitude. The perturbations to the curvature power spectrum, on the other hand, remain a small component on top of the usual spectrum of fluctuations generated by slow roll. We utilize our analytic solutions to assess the observability of the predicted non-Gaussian signatures and show that, if present, only very sharp steps on scales larger than ∼2Gpc are likely to be able to be detected by Planck. Such features are not only consistent with WMAP7 data, but can also improve its likelihood by 2Δln L≈12 for two extra parameters, the step location and height. If this improvement were due to a slow roll violating step as considered here, a bispectrum or corresponding polarization power spectrum detection would provide definitive checks as to its primordial origin.

Original languageEnglish (US)
Article number023531
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Issue number2
StatePublished - Jan 26 2012
Externally publishedYes

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Physics and Astronomy (miscellaneous)


Dive into the research topics of 'Non-Gaussianity from step features in the inflationary potential'. Together they form a unique fingerprint.

Cite this