Primordial tensor non-Gaussianities from general single-field inflation with non-Bunch-Davies initial states

It has been found that the primordial non-Gaussianity of the curvature perturbation in the case of non-Bunch-Davies initial states can be enhanced compared with those in the case of the Bunch-Davies one due to the interactions among the perturbations on subhorizon scales. The purpose of the present...

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Bibliographic Details
Published in:arXiv.org 2020-04
Main Authors: Akama, Shingo, Hirano, Shin'ichi, Kobayashi, Tsutomu
Format: Article
Language:English
Subjects:
Mathematical analysis
Perturbation
Tensors
Online Access:Get full text
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Summary:It has been found that the primordial non-Gaussianity of the curvature perturbation in the case of non-Bunch-Davies initial states can be enhanced compared with those in the case of the Bunch-Davies one due to the interactions among the perturbations on subhorizon scales. The purpose of the present paper is to investigate whether tensor non-Gaussianities can also be enhanced or not by the same mechanism. We consider general gravity theory in the presence of an inflaton, and evaluate the tensor auto-bispectrum and the cross-bispectrum involving one tensor and two scalar modes with the non-Bunch-Davies initial states for tensor modes. The crucial difference from the case of the scalar auto-bispectrum is that the tensor three-point function vanishes at the flattened momentum triangles. We point out that the cross-bispectrum can potentially be enhanced at non-trivial triangle shapes due to the non-Bunch-Davies initial states.
ISSN:2331-8422
DOI:10.48550/arxiv.2003.10686