Feeding your inflaton: nonGaussian signatures of interaction structure
Abstract
Primordial nonGaussianity is generated by interactions of the inflaton field, either selfinteractions or couplings to other sectors. These two physically different mechanisms can lead to nearly indistinguishable bispectra of the equilateral type, but generate distinct patterns in the relative scaling of higher order moments. We illustrate these classes in a simple effective field theory framework where the flatness of the inflaton potential is protected by a softly broken shift symmetry. Since the distinctive difference between the two classes of interactions is the scaling of the moments, we investigate the implications for observables that depend on the series of moments. We obtain analytic expressions for the Minkowski functionals and the halo mass function for an arbitrary structure of moments, and use these to demonstrate how different classes of interactions might be distinguished observationally. Our analysis casts light on a number of theoretical issues, in particular we clarify the difference between the physics that keeps the distribution of fluctuations nearly Gaussian, and the physics that keeps the calculation under control.
 Publication:

Journal of Cosmology and Astroparticle Physics
 Pub Date:
 January 2012
 DOI:
 10.1088/14757516/2012/01/034
 arXiv:
 arXiv:1109.2985
 Bibcode:
 2012JCAP...01..034B
 Keywords:

 Astrophysics  Cosmology and Nongalactic Astrophysics;
 High Energy Physics  Phenomenology;
 High Energy Physics  Theory
 EPrint:
 33 pages (plus appendices), 3 figures. V2: references added, some minor clarifications. Accepted for publication in JCAP