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Decoding the bispectrum of single-field inflation
journal contribution
posted on 2023-06-07, 20:25 authored by Raquel H Ribeiro, David SeeryDavid SeeryGalileon fields arise naturally from the decoupling limit of massive gravities, and possess special self-interactions which are protected by a spacetime generalization of Galilean symmetry. We briefly revisit the inflationary phenomenology of Galileon theories. Working from recent computations of the fluctuation Lagrangian to cubic order in the most general model with second-order equations of motion, we show that a distinct shape is present but with suppressed amplitude. A similar shape has been found in other higher-derivative models. It may be visible in a theory tuned to suppress the leading-order shapes, or if the overall bispectrum has large amplitude. Using a partial-wave expansion of the bispectrum, we suggest a possible origin for the frequent appearance of this shape. It follows that models with very disparate microphysics can produce very similar bispectra. We argue that it may be more profitable to distinguish these models by searching for relations between the amplitudes of these common shapes. We illustrate this method using the example of DBI and k-inflation.
History
Publication status
- Published
Journal
Journal of Cosmology and Astroparticle PhysicsExternal DOI
Issue
10Volume
2011Page range
027Department affiliated with
- Physics and Astronomy Publications
Notes
Author list in alphabetical orderFull text available
- No
Peer reviewed?
- Yes