Classical and quantum dynamics during inflation

在早期宇宙加速膨胀（“暴胀”）期间，场的经典演化可以建立一个理想化的均匀和各向同性的宇宙学，但是量子涨落不可避免地在所有可观察的尺度上（以及更远的尺度上）产生不均匀性和各向异性。这个项目将探索标量场、矢量场和张量场（包括原始密度场和引力波）中产生的涨落的性质，以及我们如何将这些预测与当前和未来的观测结果进行比较，以确定早期宇宙中存在的暴胀动力学和物理自由度。特别是，我们将采用随机方法来模拟暴胀动力学，把量子涨落看作随机噪声，以及最近发展起来的计算原初密度场全概率分布函数的非微扰方法。我们将描述这种非高斯分布的性质，并将我们的结果应用于计算极端物体的丰度，如超紧凑的迷你晕和原始黑洞在一些模型中预测。该项目涉及分析和数值工作的结合。

The classical evolution of fields during a period of accelerated expansion in the very early universe("inflation") can establish an idealised homogeneous and isotropic cosmology, but quantumfluctuations inevitably generate inhomogeneities and anisotropies on all observable scales (andbeyond). This project will explore the nature of the fluctuations produced in scalar, vector and tensorfields, including the primordial density field and gravitational waves, and how we may compare thesepredictions against current and future observations to identify the inflationary dynamics and physicaldegrees of freedom present in the very early universe.In particular we will employ the stochastic approach to modelling inflationary dynamics, incorporatingquantum fluctuations as a stochastic noise, and the recently developed non-perturbative techniques tocalculate the full probability distribution function for the primordial density field. We will characterisethe nature of this non-Gaussian distribution, and apply our results to calculate the abundance ofextreme objects such as ultra-compact mini-halos and primordial black holes predicted in somemodels. This project involves a combination of analytic and numerical work.