标题： 天作之合：连接膨胀宇宙学中的可观测量 显示英文标题

标题： A Match Made in Heaven: Linking Observables in Inflationary Cosmology

摘要： 宇宙膨胀场和引力子扰动的关联函数是早期宇宙学的基本可观测量，并且仍然是观测的主要目标。 在这项工作中，我们提出了以下问题：这些可观测量是否彼此独立？ 我们发现，在膨胀扰动理论的宇称奇异数域中，答案是否定的！ 在之前的工作中，我们推导了一个关联函数到关联函数的分解公式，该公式指出在基础理论的一些温和假设下，宇称奇异关联函数可以分解为较低点关联函数。 在这项工作中，我们证明了这些假设在动态Chern-Simons引力中得到满足，在这种引力中，最小膨胀作用加上了膨胀场与引力Chern-Simons项之间的耦合。 这种理论产生了曲率扰动的宇称奇异四点谱，我们证明这种四点谱可以完全由由于膨胀场与引力子之间最小耦合产生的四点谱以及在该理论中接受宇称奇异修正的引力子功率谱表示。 四点谱在这个混合膨胀-引力子三点谱上是二次的，因此可以被解释为“双重复制”。 我们对于宇称奇异四点谱的最终表达式是一个相对简单的外部动量的有理化和分解函数。 显示英文摘要

摘要： Cosmological correlation functions of inflaton and graviton perturbations are the fundamental observables of early universe cosmology and remain a primary target for observations. In this work, we ask the following question: are these observables independent of one another? We find that in the parity-odd sector of inflationary perturbation theory, the answer is a resounding no! In earlier work we derived a correlator-to-correlator factorisation formula which states that parity-odd correlators factorise into lower-point correlators under some mild assumptions on the underlying theory. In this work, we show that these assumptions are satisfied in dynamical Chern-Simons gravity where the action of minimal inflation is augmented by a coupling between the inflaton and the gravitational Chern-Simons term. Such a theory gives rise to a parity-odd trispectrum of curvature perturbations, and we show that such a trispectrum can be expressed solely in terms of the bispectrum that arises due to the minimal coupling between the inflaton and graviton, and the graviton power spectrum which receives a parity-odd correction in this theory. The trispectrum is quadratic in this mixed inflaton-graviton bispectrum and can therefore be interpreted as a ``double copy". Our final expression for the parity-odd trispectrum is a relatively simple function of the external momenta that is rational and factorised.