(Small) resonant non-gaussianities: Signatures of a discrete shift symmetry in the effective field theory of inflation

Siavosh R. Behbahani, Anatoly Dymarsky, Mehrdad Mirbabayi, Leonardo Senatore

Research output: Contribution to journalArticlepeer-review

61 Scopus citations

Abstract

We apply the Effective Field Theory of Inflation to study the case where the continuous shift symmetry of the Goldstone boson π is softly broken to a discrete subgroup. This case includes and generalizes recently proposed String Theory inspired models of Inflation based on Axion Monodromy. The models we study have the property that the 2-point function oscillates as a function of the wavenumber, leading to oscillations in the CMB power spectrum. The non-linear realization of time diffeomorphisms induces some self-interactions for the Goldstone boson that lead to a peculiar non-Gaussianity whose shape oscillates as a function of the wavenumber. We find that in the regime of validity of the effective theory, the oscillatory signal contained in the n-point correlation functions, with n > 2, is smaller than the one contained in the 2-point function, implying that the signature of oscillations, if ever detected, will be easier to find first in the 2-point function, and only then in the higher order correlation functions. Still the signal contained in higher-order correlation functions, that we study here in generality, could be detected at a subleading level, providing a very compelling consistency check for an approximate discrete shift symmetry being realized during inflation.

Original languageEnglish
Article number036
JournalJournal of Cosmology and Astroparticle Physics
Volume2012
Issue number12
DOIs
StatePublished - Dec 2012

Keywords

  • ination
  • non-gaussianity

ASJC Scopus subject areas

  • Astronomy and Astrophysics

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