Quantum fluctuations during cosmic inflation

宇宙膨胀描述了宇宙在非常早期的宇宙中以超高能量加速膨胀。这是对宇宙大规模同质性和各向同性的最简单解释，但至关重要的是，它也产生了原始密度扰动，进而形成了我们宇宙的大规模结构。膨胀过程中的小尺度量子场波动被迅速膨胀到天文尺度所卷走。因此，膨胀产生的原始微扰是对有效场论和超高能下不同粒子种类的探索。本项目将探索不同理论模型下的暴涨动力学和原始微扰的产生。我们将研究宇宙微波背景和大规模星系调查中微扰的统计性质如何对粒子物理理论敏感。特别是，我们将考虑更高自旋场在标量(密度)和张量(引力波)功率谱中的印记，以及更高阶关联器和交叉关联。我们还将考虑长波量子涨落在膨胀期间场值的随机分布中所起的作用，甚至超出我们的可观测视界。最终，我们的目标是对不同通胀理论模型的证据进行定量统计比较。

Cosmological inflation describes an accelerated expansion of the Universe at ultra-high energies in the very early universe. It is the simplest explanation for the large-scale homogeneity and isotropy of our Universe but, crucially, it also generates primordial density perturbations which go on to form the large-scale structure of our universe. Small-scale quantum field fluctuations during inflation are swept up by the rapid expansion to astronomical scales. Primordial perturbations produced by inflation are thus a probe of the effective field theory and different particle species at ultra-high energies.This project will explore inflationary dynamics in different theoretical models and the generation of primordial perturbations. We will investigate how the statistical properties of perturbations in the cosmic microwave background and large-scale galaxy surveys are sensitive to the particle physics theory. In particular we will consider the imprint of higher spin fields in the scalar (density) and tensor (gravitational wave) power spectra and higher-order correlators and cross-correlations. We will also consider the role that long-wavelength quantum fluctuations play in the stochastic distribution of field values during inflation on scales even beyond our observable horizon. Ultimately our aim is to make quantitative statistical comparisons of the evidence for different theoretical models of inflation.