Professor, Canada Research Chair (Tier 1)

我的研究计划的总体主题是用新的宇宙学观测来检验基础物理学。 观测和实验宇宙学在过去几年中进入了"黄金时代“。实验已经产生了宇宙微波背景（CMB）温度分布的高精度地图。高质量的CMB偏振图将在未来五年内提供。用新的光学望远镜观测到的有关大尺度宇宙结构的数据正在迅速积累。 21厘米红移巡天将为探测这种结构提供一个新的窗口。加拿大在这些观测工作中发挥着重要作用（例如麦吉尔大学的Matt Dobbs教授）。我计划研究如何利用这些令人兴奋的新数据来探索高能物理的各个方面。 我计划追求的一条研究途径是在新的观测窗口中寻找拓扑缺陷的信号，如宇宙弦。在标准模型之外的许多粒子物理模型中都预测到拓扑缺陷，在这种情况下，不可避免地在早期宇宙中出现并持续到现在。在宇宙学观测中寻找这种缺陷的信号是探索粒子物理学的一种方式，它是对加速器研究的补充。我们将在不同的观测窗口中计算出弦的特定信号，并开发统计工具，当信号嵌入背景噪声中时，可以看到这些信号。在宇宙中观察到的结构的种子是在非常早期的宇宙中奠定的，在那里新的基础物理有望运作。空间的膨胀是一个宇宙学显微镜，让我们用宇宙学实验来探索基础物理学。关于早期宇宙的数据被编码在传播到现在的宇宙学波动中。 我计划利用超弦理论的基本原理，在最高的能量尺度上发展对早期宇宙的理解。我们过去对“弦气体宇宙学”的研究表明，早期宇宙的图景将与基于常规粒子物理学的宇宙学的天真推断完全不同。缺少的是对早期阶段的一致动力学描述。我们工作的目标之一是提供一个基于弦理论的非常早期宇宙的改进动力学图像。对非常早期宇宙的更好理解将产生新的和更一致的暴胀实现，但也可能导致替代的早期宇宙场景与宇宙学观测的具体预测。我还计划工作在新的暗能量模型的基础上的理论与轴子，对暴胀再加热，对宇宙学扰动的反反应，并通过等离子体效应嵌入缺陷的稳定。

The overall theme of my research proposal is to test fundamental physics with new cosmological observations. Observational and experimental cosmology have over the past years entered a ``golden age''. Experiments have produced high precision maps of the temperature distribution of the cosmic microwave background (CMB). High quality CMB polarization maps will become available over the next five years. Data concerning the structure of the universe on large scales as seen from new optical telescopes is accumulating at a rapid rate. 21cm redshift surveys will provide a new window to probe this structure. Canada is playing an important role in these observational efforts (e.g. Prof. Matt Dobbs at McGill). I plan to study ways to use this exciting new data to probe aspects of high energy physics. One avenue of research which I plan to pursue is to search for signals of topological defects such as cosmic strings in new observational windows. Topological defects are predicted in many particle physics models beyond the Standard Model, and in this case inevitably arise in the early universe and persist to the present time. Looking for signals of such defects in cosmological observations is a way to probe particle physics which is complementary to accelerator studies. We will work out the specific signals of strings in various observational windows and develop statistical tools with which the signals can be seen when they are embedded in background noise.The seeds for the structures which are observed in the cosmos were laid down in the very early universe at energies where new fundamental physics is expected to be operational. The expansion of space is a cosmological microscope which lets us probe fundamental physics with cosmological experiments. The data about the early universe is encoded in cosmological fluctuations which propagate to the present time. I plan to use fundamental principles of superstring theory to develop an understanding of the very early universe at the highest energy scales. Our past work on ``string gas cosmology" indicates that the picture of the early universe will be radically different from what naive extrapolation of convention particle physics-based cosmology would yield. What is missing is a consistent dynamical description of the early phase. One of the goals of our work is to provide an improved dynamical picture of the very early universe based on string theory. An improved understanding of the very early universe will generate new and more consistent realizations of inflation, but may also lead to alternative early universe scenarios with specific predictions for cosmological observations.I also plan to work on new dark energy models based on theories with axions, on inflationary reheating, on the back-reaction of cosmological perturbations, and on the stabilization of embedded defects via plasma effects.