Professor, Canada Research Chair (Tier 1)

我的研究提案的总主题是用新的宇宙学观测来检验基础物理学。在过去的几年里，观测和实验宇宙学已经进入了一个“黄金时代”。实验已经制作了高精度的宇宙微波背景(CMB)温度分布图。高质量的CMB偏振图将在未来五年内推出。从新的光学望远镜上看到的关于大尺度宇宙结构的数据正在快速积累。21厘米的红移测量将为探索这一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，麦吉尔的马特·多布斯教授)。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。我计划从事的一种研究途径是在新的观测窗口中寻找拓扑缺陷的信号，例如宇宙弦。在标准模型之外的许多粒子物理模型中都预测到了拓扑缺陷，在这种情况下，拓扑缺陷不可避免地出现在早期宇宙中，并持续到现在。在宇宙学观测中寻找此类缺陷的信号是探索粒子物理学的一种方式，这是对加速器研究的补充。我们将计算出各种观测窗口中弦的特定信号，并开发统计工具，当信号嵌入背景噪音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发挥作用。太空扩张是一台宇宙学显微镜，它让我们可以通过宇宙学实验来探索基础物理。关于早期宇宙的数据被编码为宇宙学的涨落，并传播到现在。我计划使用超弦理论的基本原理来发展对最高能量尺度下非常早期的宇宙的理解。我们过去在弦气体宇宙学方面的工作表明，早期宇宙的图景将与传统的基于粒子物理的宇宙学的天真外推产生根本不同的结果。缺少的是对早期阶段的一致动态描述。我们工作的目标之一是在弦理论的基础上提供非常早期的宇宙的改进的动力学图像。对极早期宇宙的更好理解将产生新的和更一致的暴涨认识，但也可能导致对宇宙观测的特定预测的替代早期宇宙情景。我还计划基于轴子理论、膨胀再热理论、宇宙学微扰的反向反应理论以及通过等离子体效应稳定嵌入的缺陷的理论，致力于新的暗能量模型。

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.