Primordial non-Gaussianities of gravitational waves beyond Horndeski theories
Primordial non-Gaussianities of gravitational waves beyond Horndeski theories
复制标题
霍恩德斯基理论之外的引力波本初非高斯性
DOI：
10.1103/physrevd.93.043519
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Tsutomu Kobayashi
中科院分区：
文献类型：
--
作者：
Yuji Akita;Tsutomu Kobayashi
We clarify the features of primordial non-Gaussianities of tensor perturbations in Gao’s unifying framework of scalar-tensor theories. The general Lagrangian is given in terms of the ADM variables so that the framework maintains spatial covariance and includes the Horndeski theory and Gleyzes-Langlois-Piazza-Vernizzi (GLPV) generalization as specific cases. It is shown that the GLPV generalization does not give rise to any new terms in the cubic action compared to the case of the Horndeski theory, but four new terms appear in more general theories beyond GLPV. We compute the tensor three-point correlation functions analytically by treating the modification to the dispersion relation as a perturbation. The relative change in the three-point functions due to the modified dispersion relation is only mildly configuration dependent. When the effect of the modified dispersion relation is small, there is only a single cubic term generating squeezed non-Gaussianity, which is the only term present in general relativity. The corresponding non-Gaussian amplitude has a fixed and universal feature, and hence offers a “consistency relation” for primordial tensor modes in a quite wide class of single-field inflation models. All the other cubic interactions are found to give peaks at equilateral shapes.
