Shapes and features of the primordial bispectrum

Jinn Ouk Gong, Gonzalo A. Palma, Spyros Sypsas

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


If time-dependent disruptions from slow-roll occur during inflation, the correlation functions of the primordial curvature perturbation should have scale-dependent features, a case which is marginally supported from the cosmic microwave background (CMB) data. We offer a new approach to analyze the appearance of such features in the primordial bispectrum that yields new consistency relations and justifies the search of oscillating patterns modulated by orthogonal and local templates. Under the assumption of sharp features, we find that the cubic couplings of the curvature perturbation can be expressed in terms of the bispectrum in two specific momentum configurations, for example local and equilateral. This allows us to derive consistency relations among different bispectrum shapes, which in principle could be tested in future CMB surveys. Furthermore, based on the form of the consistency relations, we construct new two-parameter templates for features that include all the known shapes.

Original languageEnglish
Article number016
JournalJournal of Cosmology and Astroparticle Physics
Issue number5
StatePublished - 8 May 2017

Bibliographical note

Publisher Copyright:
© 2017 IOP Publishing Ltd and Sissa Medialab srl.


  • cosmological perturbation theory
  • inflation
  • non-gaussianity


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