Inflationary Cosmology: Preparing the Theory to Match the Observations

在观测宇宙学最近和即将取得的进展的推动下，这项研究计划将开发必要的理论框架，以研究可以与丰富的可用数据进行检验的现实膨胀模型。具体地说，它将侧重于预测曲率扰动中潜在可检测到的非高斯性水平以及可观测到的引力波背景的情景。考虑到与非常早期的宇宙相关的高能标度，在更高维度的统一场论(如弦/M理论)的背景下发展暴涨情景是很自然的。我们将研究膨胀模型，其中我们可观察到的宇宙的加速膨胀是由于一个或多个沿更高维度的扭曲喉部几何形状传播的“膜”的运动而产生的。我们将发展一种解析形式来解释由等温模引起的绝热曲率扰动的演化。这将被用来计算曲率微扰的三点和四点关联函数。我们将研究产生的任何非高斯性的水平和尺度依赖性如何依赖于所假定的初始真空态的性质。我们将推导出可观测参数之间的一致性方程，这些参数原则上可以用来排除或证实不同的通胀模型。这提供了在能量尺度上直接限制宇宙物理的可能性，任何形式的地面实验都无法获得，并将产生关于宇宙起源、演化和大尺度结构的独特信息。

Motivated by recent and forthcoming advances in observational cosmology, this program of research will develop the theoretical framework necessary for studying realistic inflationary models that can be tested against the wealth of available data. Specifically, it will focus on scenarios that predict potentially detectable levels of non-Gaussianity in the curvature perturbation as well as an observable gravitational wave background. Given the high energy scales associated with the very early universe, it is natural to develop inflationary scenarios within the context of higher-dimensional, unified field theories such as string/M-theory. We will study models of inflation where the accelerated expansion of our observable universe arises due to the motion of one or more `branes' propagating down a warped throat geometry of the higher dimensions. An analytical formalism will be developed that can account for the evolution of the adiabatic curvature perturbation due to isocurvature modes. This will be employed to calculate the three- and four-point correlation functions of the curvature perturbation. We will investigate how the level and scale-dependence of any non-Gaussianity that is generated depends on the nature of the initial vacuum state that is assumed. We will derive consistency equations between observable parameters that in principle could be employed to rule out or confirm different inflationary models. This offers the possibility of directly constraining the physics of the universe at energy scales that are inaccessible to any form of terrestrial experiment and will yield unique information on the origin, evolution and large-scale structure of the universe.