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arXiv 1209.1701gr-qcastro-ph.COhep-th
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宇宙学扰动规范不变量action的唯一性

Uniqueness of the gauge invariant action for cosmological perturbations

Tomislav Prokopec, Jan Weenink

摘要:

在二阶微扰理论中,单场暴胀模型中规范不变微扰有不同的定义。因此,相应的规范不变三次作用量不具有相同的形式。在这里,我们表明,立方行动的一个选择规范不变变量是唯一的,在以下意义上:行动的任何其他非线性相关的变量可以带来相同的散装行动,加上额外的边界条件。这些边界项对应于超曲面的选择,并对双谱产生额外的、不连续的贡献。我们还讨论了作用关于共形框架的唯一性。当用均匀场超曲面上的规范不变曲率扰动表示时,宇宙学扰动的作用量具有唯一的形式,与原始的爱因斯坦或乔丹框架无关。重要的是,规范不变的同动曲率微扰是与标架无关的,这使得它非常有助于证明两个标架的量子等价性,从而有助于计算非最小耦合理论(如希格斯暴胀)中的量子效应。

英文摘要:

In second order perturbation theory different definitions are known of gauge invariant perturbations in single field inflationary models. Consequently the corresponding gauge invariant cubic actions do not have the same form. Here we show that the cubic action for one choice of gauge invariant variables is unique in the following sense: the action for any other, non-linearly related variable can be brought to the same bulk action, plus additional boundary terms. These boundary terms correspond to the choice of hypersurface and generate extra, disconnected contributions to the bispectrum. We also discuss uniqueness of the action with respect to conformal frames. When expressed in terms of the gauge invariant curvature perturbation on uniform field hypersurfaces the action for cosmological perturbations has a unique form, independent of the original Einstein or Jordan frame. Crucial is that the gauge invariant comoving curvature perturbation is frame independent, which makes it extremely helpful in showing the quantum equivalence of the two frames, and therefore in calculating quantum effects in nonminimally coupled theories such as Higss inflation.

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