高能电子成像实验的进展及展望||本周物理学术讲座

报告人：盖炜，ANL/清华大学

时间： 6月22日（周四）10:00

单位： 中科院高能物理研究所

地点：化学楼C305

用于高能量密度物质诊断的高能电子成像技术已由概念进入到实验验证阶段，报告将介绍最近由中国科学院近代物理研究所和清华大学合作的50MeV电子成像实验。实验结果表明其空间分辨可以达µm量级，且很好地实现了对mm厚度Si靶的密度分辨，初步验证了其对于惯性约束核聚变初期靶丸密度演化的诊断的可行性。同时，将探讨高能电子成像技术在其他领域的应用。

报告人：Xin Fan，University of Denver

时间：6月20日（周二）14:00

单位：清华大学物理系

地点：理科楼C302报告厅

In this talk, we will discuss our research on the spin-orbit effects of transverse spins in ferromagnetic metals. We find that the ferromagnetic metals not only have finite spin-orbit effects, but also exhibit an unusual symmetry as if the spins are rotated by the magnetization of the ferromagnetic metals. We will discuss the implications of our finding on the fundamental understanding of the spin-orbit effects, as well as on the potential application in spin-orbit torque based magnetic memories.

报告人：Suddhasattwa Brahma，复旦大学

时间：6月21日（周三）10:00

单位：北京师范大学物理系

地点：电子楼105

In this talk, I shall discuss deformations in fundamental space-time structures appearing from non-perturbative corrections in loop quantum gravity (LQG). This gives rise to a non-Riemannian geometry for quantum space-time with 'signature-change' being the main physical effect. Additionally, phenomenological consequences of such space-times, in the form of modified dispersion relations in the flat limit, shall also be demonstrated. Finally, a brief discussion on the possible relationship between LQG and non-commutative geometry shall be initiated.

报告人：Chris Pope，Texas A&M University

时间：6月21日（周三）15:30

单位：北京师范大学物理系

地点：科技楼C区602

It has been argued that the global E_n duality symmetry that arises when eleven-dimensional supergravity is compactified on an n-torus is actually a symmetry of the full uncompactified theory. In one of the boldest versions of this approach, it has been argued by West that there is an underlying description of eleven-dimensional supergravity, and M-theory, based on the infinite-dimensional E_{11} algebra. In this talk some recent work is described in which we study West's approach, and argue that some problems that arise in his formulation may be overcome if one enlarges the symmetry algebra even further, to the so-called Tensor Hierarchy algebra.

报告人：于福升，兰州大学

时间：6月22日（周四）10:30

单位：北京航空航天大学

地点：Room 513, Main Building

CP violation plays an important role in interpreting the matter-antimatter asymmetry in the Universe and searching for new physics beyond the Standard Model. So far CP violation has not been observed in the charm sector. Searching for CPV is one major goal of charm physics. We find new measurable effect of CP asymmetries in the non-leptonic charmed hadron decaying into neutral kaons in the Cabibbo-favored and doubly Cabibbo-suppressed processes. Compared to the CP asymmetries in the singly Cabibbo-suppressed processes, the advantages of this new effect include avoiding ambiguities from penguin contributions in theory, with only tree-level amplitudes available to be extracted from the data of branching fractions. Besides, such processes having larger branching fractions benefits for measurements in experiment. The values of such CP asymmetries are at the order of 10^{-3} and hence are accessible by the LHCb and Belle II experiments in the near future. Besides, the measurement and determination of time-dependent CP asymmetries at t=0 is a smoking gun of direct CP violation in charm decays and signal of new physics.

报告人：龙江，ULB

时间： 6月22日（周四）15:30

单位： 中科院高能物理研究所

地点：Theoretical Physics Division，319

Mutual information measures the entanglement between two disjoint regions. Using defect operator OPE and conformal block expansion,we show that the bilinear operators contribute to mutual information of two balls region universally. We check the analytic result numerically for various free boson and free fermion theories.

报告人：Xilong Fan，LIGO@Tsinghua University

时间： 6月22日（周四）16:00

单位：北京大学科维理天文与天体物理研究中心

地点：KIAA-PKU Auditorium

The first directly detection of gravitational wave (GW) opens the new era of astronomy: the gravitational wave astronomy.  I will briefly introduce the role of high-frequency GW signals in studies of multi-messenger joint observations, GW source population and cosmology.  I will present a Bayesian approach to multi-messenger astronomy and its applications on GW-host galaxy and GW-short gamma-ray burst.  The strong lensed GW-EM system as an astrophysical probe, especially on measuring the GW speed and constraining cosmology parameters, will also be discussed.

报告人：Jingyong Ye，the University of Texas at San Antonio

时间： 6月22日（周四）16:00

单位：清华大学物理系

地点：郑裕彤讲堂

In this talk I will present two unique biosensors for both in vitro and in vivo applications. First, I will describe a photonic crystal based biosensor for label-free bioassays. As opposed to a conventional optical microcavity sensor that has a closed structure with its cavity layer sandwiched between two highly reflective surfaces, the photonic crystal sensor we developed possesses a novel open optical microcavity. The open configuration allows the sensing layer to be easily functionalized and directly exposed to analyte molecules for label-free bioassays through monitoring the change in resonant conditions of the open microcavity. A wide range of applications can be facilitated by the unique open-microcavity biosensor. In particular, two different applications will be covered in this talk. One is for label-free measurements of cardiac biomarkers- Troponin I (cTnI). The sensor is functionalized with antibodies against cTnI for sensitive detection of cTnI with a concentration as low as 0.1 ng mL-1. The other application is to use the sensor for the study of interactions between different peptides and FvTox1- a toxin produced by a soil borne pathogen that causes sudden death syndrome in soybean plants. Furthermore, I will discuss the development of a novel two-photon optical fiber fluorescence (TPOFF) probe and its applications for in vivo biosensing, such as real-time monitoring nanoparitcle-based drug delivery in a live mouse model.