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Journal Article

#### Resonant non-Gaussianity with equilateral properties

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##### Fulltext (public)

1211.0070

(Preprint), 4MB

JCAP4_040.pdf

(Any fulltext), 2MB

##### Supplementary Material (public)

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##### Citation

Gwyn, R., Rummel, M., & Westphal, A. (2013). Resonant non-Gaussianity with equilateral
properties.* Journal of Cosmology and Astroparticle Physics,* *4*:
040. doi:10.1088/1475-7516/2013/04/040.

Cite as: http://hdl.handle.net/11858/00-001M-0000-000E-74C2-4

##### Abstract

We discuss the effect of superimposing multiple sources of resonant
non-Gaussianity, which arise for instance in models of axion inflation. The
resulting sum of oscillating shape contributions can be used to "Fourier
synthesize" different non-oscillating shapes in the bispectrum. As an example
we reproduce an approximately equilateral shape from the superposition of
${\cal O}(10)$ oscillatory contributions with resonant shape. This implies a
possible degeneracy between the equilateral-type non-Gaussianity typical of
models with non-canonical kinetic terms, such as DBI inflation, and an
equilateral-type shape arising from a superposition of resonant-type
contributions in theories with canonical kinetic terms. The absence of
oscillations in the 2-point function together with the structure of the
resonant $N$-point functions, imply that detection of equilateral
non-Gaussianity at a level greater than the PLANCK sensitivity of
$f_{NL}\sim{\cal O}(5)$ will rule out a resonant origin. We comment on the
questions arising from possible embeddings of this idea in a string theory
setting.