Classical and quantum dynamics during inflation

在早期宇宙加速膨胀时期（“暴胀”）的经典场演化可以建立一个理想的均匀和各向同性宇宙学，但量子涨落不可避免地在所有可观测尺度（及更大尺度）上产生非均匀性和各向异性。该项目将探索标量场、矢量场和张量场（包括原始密度场和引力波）产生的波动的本质，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，将量子涨落作为随机噪声，以及最近开发的非摄动技术来计算原始密度场的全概率分布函数。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，例如在某些模型中预测的超紧凑迷你晕和原始黑洞。这个项目涉及到解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.