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Journal Article

Resonant non-Gaussianity with equilateral properties


Gwyn,  Rhiannon
Quantum Gravity & Unified Theories, AEI-Golm, MPI for Gravitational Physics, Max Planck Society, Golm, DE;

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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
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.