Scalar parity-odd trispectrum from gravitational Chern-Simons interaction vertices
Abstract
In this paper, we explore parity violation in a scalar trispectrum from a dynamical Chern-Simons gravity theory. So far, a graviton-mediated diagram with two vertexes being of general relativity has been studied in this theory by taking into account the impact of a modified dispersion relation of gravitons on graviton's bulk propagators. We instead study a parity-odd trispectrum from both a graviton-mediated diagram, where one of the two vertexes originates from the Chern-Simons term, and a contact diagram by using the bulk propagators in general relativity. After computing the scalar-scalar-tensor cubic interactions and the scalar quartic ones originating from the Chern-Simons term, first we show that the resultant parity-odd trispectrum vanishes in the case of Bunch-Davies initial conditions, which is consistent with a no-go theorem for a non-vanishing parity-odd trispectrum. Then, we discuss a way to acquire a non-vanishing parity-odd trispectrum from the viewpoint of non-Bunch-Davies initial conditions.
Cite
@article{arxiv.2505.16920,
title = {Scalar parity-odd trispectrum from gravitational Chern-Simons interaction vertices},
author = {Giorgio Orlando and Shingo Akama and Chunshan Lin},
journal= {arXiv preprint arXiv:2505.16920},
year = {2026}
}
Comments
26 pages, 2 figures; v2: some parts have been improved and reorganized. The appendix was moved to Section 4. The current Section 6 now includes the computation of the graviton-mediated diagram; matches published version in JCAP