报告讲座
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格物致理73期：BESIII实验上的超子物理研究进展
利用BESIII实验收集的J/psi和psi(3686)大量实验数据，为探究量子关联的正反超子对的产生和衰变提供了新的思路。在BESIII最近的一系列研究中，观察到J/psi和psi(3686)衰变到超子对时呈现出横向极化现象。由于存在非零极化，超子和反超子衰变参数得以首次相互独立确定。通过比较超子和反超子的衰变参数，可以精确验证超子衰变过程的CP对称性。
发布者： 发布时间：2024-11-01 09:22:48 -
格物致理72期：An Introduction to Solitonic Perturbation Methods
In this talk we will talk about more mathematical and fundational aspects of quantization in general, focusing on its difficulties instead of great achievements. Especially, we will talk about the second kind of divergence in quantum field theory, as a motivation to organically integrate the soitonic contribution into QFT as a whole, and the quantization at the presence of a kink. Recall that renormalization is crucial in obtaining finite order-by-order contributions in formal perturbation theory. However, the matching of renormalization schemes between different topological sectors was for a long time not well defined hence lead to ambiguity. In this talk we will also try to answer the question: If a vacuum sector Hamiltonian is regularized by an energy cutoff, how is the one-kink sector Hamiltonian regularized?
发布者： 发布时间：2024-10-14 14:14:16 -
格物致理70期：Cosmology: A Golden Era（宇宙学的黄金时代）
Cosmology, the understanding of the evolution of entire Universe, has progressed very fast in the past several decades with the advances of modern telescopes. I will give a brief overview of the modern cosmology of the last century and highlight its phenomenal successes and distinctive challenges. I will explain how and why the measurements of cosmic microwave background radiation, the relics of the primordial elements, and the galaxy distribution on large scales can improve our understanding of the hot big bang. Then I will also discuss its distinctive challenges, present the observational frontiers for this (next) decade of cosmology, highlighting where the new physics may possibly emerge.
发布者： 发布时间：2024-06-11 10:32:29 -
格物致理71期：Observation of the energetic particles using LND
Lunar Lander Neutron and Dosimetry (LND) experiment onboard the Chang’E-4 lander is the first charged particle telescope working on the lunar (far-side) surface, and it can effectively measure the radiation environment of the lunar far-side surface during solar eruptions. The theme of talk will include the lunar radiation environment, the SEP observations, the albedo (secondary) proton generated on the lunar surface, and a brief introduction of the dawn-dusk asymmetry characteristic of the lower energy GCRs.
发布者： 发布时间：2024-06-11 10:29:31 -
格物致理69期：Fermi耀变体光学波段能谱演化特征及其物理机制研究
耀变体光学波段能谱演化行为比较复杂，一直没有发现统一的行为特征，其中的物理机制也缺乏清晰的理解。本报告通过大样本的费米耀变体研究，介绍最新的研究结果。1. 首次发现了费米耀变体存在两种统一的光学波段谱指数演化模式，一种是当变亮时，源会变红（谱变软），然后趋于稳定，并定义为（RSWB），另一种是当变亮时，源会变蓝（谱变硬），然后趋于稳定，并定义为（BSWB）模式。2.首次提出了一个非线性公式，取代以往的线性拟合，很好地描述了能谱演化行为。3.构建了双成分稳谱指数理论，不仅从理论上定性地解释了谱指数演化行为，而且很好地定量地描述了能谱指数演化行为；同时很自然地解释了RSWB和BSWB这两种模式之间内在的区别和联系，以及FSRQs和BL Lac这两类天体之间的联系。4.成功地将以前发现的RWB和BWB模式纳入到新的演化模式，RWB和BWB模式可以看作是本文发现的RSWB和BSWB的特例。
发布者： 发布时间：2024-05-23 14:35:49 -
格物致理68期：星际介质的湍流特性与磁场测量
湍流是星际介质的重要物理性质，它在宇宙线加速与传播和恒星形成等过程中起到至关重要的作用。超新星遗迹是潜在的银河宇宙线加速地，同时也是星际介质湍动的重要能量来源。报告将简介当前星际介质湍流和磁场强度测量方向的研究方法和进展，并介绍通过我国新一代射电望远镜，如FAST，宇宙触角，齐鲁探天等开展宇宙线加速源周围湍流和磁场的研究项目。
发布者： 发布时间：2024-05-17 16:30:27