Full trispectrum in single field DBI inflation
Full trispectrum in single field DBI inflation
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DOI：
10.1103/physrevd.80.043527
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发表时间：
2009-05
影响因子：
5
通讯作者：
F. Arroja;S. Mizuno;K. Koyama;Takahiro Tanaka
中科院分区：
文献类型：
--
作者：
F. Arroja;S. Mizuno;K. Koyama;Takahiro Tanaka
我们计算了一个相当一般的最小耦合单场暴胀模型的原始曲率扰动的树级连通四点函数，其中暴胀子的拉格朗日量是标量场及其一阶导数的一般函数。该模型包括K膨胀和DBI膨胀作为特例。我们表明，在慢滚膨胀和小声速极限的领先顺序，有两个重要的树级图的三谱。一个是交换标量模式的图，另一个是在点处发生交互的图，即接触交互图。标量交换贡献与接触相互作用贡献相当。对于DBI-暴胀模型，在所谓的等边构型中，当四个动量矢量之间的夹角相等时，标量交换三谱最大，此时标量交换三谱的振幅比接触相互作用三谱高1个数量级.
We compute the tree-level connected four-point function of the primordial curvature perturbation for a fairly general minimally coupled single field inflationary model, where the inflaton's Lagrangian is a general function of the scalar field and its first derivatives. This model includes K inflation and DBI inflation as particular cases. We show that, at the leading order in the slow-roll expansion and in the small sound speed limit, there are two important tree-level diagrams for the trispectrum. One is a diagram where a scalar mode is exchanged and the other is a diagram where the interaction occurs at a point, i.e. a contact interaction diagram. The scalar exchange contribution is comparable to the contact interaction contribution. For the DBI-inflation model, in the so-called equilateral configuration, the scalar exchange trispectrum is maximized when the angles between the four momentum vectors are equal and in this case the amplitude of the trispectrum from the scalar exchange is 1 order of magnitude higher than the contact interaction trispectrum.