11.03
Theory of Double Beta Decay (Lecture 1)
报告人：
Dr. Frank Deppisch, UCL
时 间：
星期一 2025-11-03 13:30 - 15:30
地 点：
Tsung-Dao Lee Institute/N6F-N600-Lecture Room
Tencent Meeting：
https://meeting.tencent.com/dm/pc1JOfL5yYGi
ID: 112871085 (no password）
摘 要：
This two-lecture series provides a theoretical introduction to neutrinoless double beta (0νββ) decay. The primary motivation for studying this decay lies in its unique potential to probe fundamental symmetries of the Standard Model (SM). Specifically, it is the main probe of the potential Majorana nature of neutrinos and its discovery would show that total lepton number is violated, with profound implications for our understanding of mass generation. After establishing the context within neutrino physics, we will calculate the two-neutrino double beta decay rate, separating the phase space factor from the nuclear matrix element. We will then focus on 0νββ decay as the crucial observable of interest where we will first explore the standard mechanism of light Majorana neutrino exchange but this is not the only possibility; other beyond-the-SM physics, such as heavy sterile neutrinos, could also mediate the decay. We will conclude by examining the theoretical challenges and opportunities in probing double beta decay at current and future experiments.
报告如有变动，请查看：
https://tdli.sjtu.edu.cn/event/4516
11.04 & 11.07
Lectures on QFT anomalies (Lecture 2 & 3）
报告人：
Dr. Thors Hans Hansson, Stockholm University
Lecture 2 星期二 2025-11-04 10:00-11:30
地 点：
Tsung-Dao Lee Institute/N6F-N600-Lecture Room
Tencent Meeting：
ID: 985272068 (no password)
Lecture 3 星期五 2025-11-07 10:00-11:30
地 点：
Tsung-Dao Lee Institute/N6F-N600-Lecture Room
Tencent Meeting：
ID: 726685669 (no password)
摘 要：
Prof. Hansson will give a general introduction to QFT anomalies with a minimum of technicalities, and then to illustrate their importance with a few examples from modern condensed matter physics.
报告如有变动，请查看：
https://tdli.sjtu.edu.cn/event/4513
11.04
Pickup Ions in the Outer Heliosheath and the IBEX Energetic Neutral Atom Ribbon
报告人：
Dr. Kaijun Liu（刘凯军）
时 间：
星期二 2025-11-04 14:00 - 15:00
地 点：
Tsung-Dao Lee Institute/N6F-N601-Meeting Room
Tencent Meeting：
https://meeting.tencent.com/dm/FPqgvgV0ucwF
ID: 783355213 (no password)
摘 要：
Linear analysis as well as hybrid simulations are performed to examine the stability of pickup ions in the outer heliosheath. This is critical for the validity of the secondary energetic neutral atom (ENA) mechanism, a promising model for the enigmatic ENA ribbon observed by the Interstellar Boundary Explorer (IBEX). According to the secondary ENA mechanism, the ENA ribbon comes from pickup ions in the outer helioshealth after they charge exchange with the local interstellar neutrals. Since the charge-exchange time is about two years, the conventional secondary ENA mechanism needs the pickup ions to keep their velocity distribution at born (generally a ring-beam distribution) for years. The present study examines how the development of various plasma instabilities can quickly scatter the pickup ions. The results suggest a pickup ion scattering time of 10s days, much shorter than that needed by the conventional secondary ENA model. On the other hand, it is found that the IBEX ribbon ENA flux, observed over a full solar cycle, correlates well with the solar wind ion flux measured at 1 au after a time delay of a few years. This supports the secondary ENA mechanism and the time delay (between the two fluxes) is then used to estimate the heliopause distance and the heliosphere shape.
报告如有变动，请查看：
https://tdli.sjtu.edu.cn/event/4523
11.05
Field-Tunable Anisotropic Fulde-Ferrell Phase in NbSe2/CrSiTe3 Heterostructures
报告人：
Dr. Jun Li (李军), ShanghaiTech University
时 间：
星期三 2025-11-05 10:30 - 11:30
地 点：
Tsung-Dao Lee Institute/N4F-N400 - Meeting Room
Tencent Meeting：
https://meeting.tencent.com/dm/OCtYQ3UcwQ0kID: 780485134 (no password)
摘 要：
The emergence of superconductivity in two-dimensional transition metal dichalcogenides with strong spin orbit coupling (SOC) has opened new avenues for exploring exotic superconducting states, such as the Ising-type and Rashba-type superconductivities. Here, we report experimental observation of an anisotropic Fulde-Ferrell (FF) phase in few-layer NbSe2/CrSiTe3 heterostructures under in-plane magnetic fields. Through combined magnetoresistance and nonreciprocal transport measurements, we find that due to the couplings from the ferromagnetic CrSiTe3, a half-dome-shaped region emerges in the magnetic field-temperature (B-T) diagram. Importantly, the half-dome shaped region exhibits finite second harmonic resistance with in-plane anisotropy, indicating that the superconducting state is an anisotropic FF phase. Through a symmetry analysis combined with mean field calculations, we attribute the emergent anisotropic FF phase to the CrSiTe3 layer induced Rashba SOC and three-fold rotational symmetry breaking. These results demonstrate that 1 heterostructure stacking is a powerful tool for symmetry engineering in super conductors, which can advance the design of quantum devices in atomically thin superconducting materials.
报告如有变动，请查看：
https://tdli.sjtu.edu.cn/event/4527
11.05
First-principle study of charmed meson radiative and semileptonic decay
报告人：
Dr. Yu Meng（孟雨）, 郑州大学
时 间：
星期三 2025-11-05 12:00 - 13:30
地 点：
Room 603, No.5, New Buildings of Sciences
Tencent Meeting：
https://meeting.tencent.com/dm/IMNHVk2ZWI9V
ID: 314980899, Password: 123456
摘 要：
The long-standing puzzle of charmonium decay has been an open question for decades. The decay width quoted by PDG stands in pronounced disagreement with both experimental measurement and lattice calculation. However, this month’s latest experimental measurement supports the lattice calculation and disfavors the value quoted by the PDG. In this report, I will review our lattice studies on the charmonium decay in recent years. Besides, a precise lattice determination of the radiative decay width of the strange-charm meson is presented, which provides the most stringent constraint on the decay constant of the meson. Finally, I will introduce the state-of-the-art lattice calculation of the semileptonic decay Ds→φ, the form factors of which are by far the most precise and systematic.
报告如有变动，请查看：
https://tdli.sjtu.edu.cn/event/4509
11.05
Scattering amplitudes in gauge theories
报告人：
Dr. Kaoru Hagiwara, KEK
时 间：
星期三 2025-11-05 13:30 - 15:00
地 点：
Tsung-Dao Lee Institute/N6F-N600-Lecture Room
Tencent Meeting：
https://meeting.tencent.com/dm/Jw0dWtTgJavZ
ID: 530917708 (no password)
摘 要：
In quantum field theories, scattering amplitudes are calculated perturbatively by using the plane wave solustion of the equation of motion of participating particles and its Green's functions (propagators). In gauge theories, Green's functions for the gauge particles are found only after gauge fixing. The most popular method is covariant gauge fixing, including Feynman, Landau and R_\xi gauges. The common feature among all covariant gauges is to constrain the total derivative of gauge fields, \del_mu A(x)^\mu. Accordingly, all four helicity components of virtual gauge bosons are allowed to propagate (three in Landau gauge) in each Feynman diagram, leading to subtle cancellation among interfering diagrams to obtain physically observable scattering amplitudes.
In this seriese of four lectures, I will introudce the Feynman Diagram (FD) gauge, in which the scalar component of the helicity states of virtual gauge bosons are not allowed to propagate (in case of massless gauge bosons of QED and QCD), or replaced by the Goldstone boson (in case of massive weak bosons). We have modified the helicity amplitude calculation code (HELAS) inside MadGraph that allows us to obtain arbitrary tree-level scattering amplitudes in the FD gauge, for the SM and BSM models with SMEFT operators. No subtle cancellation among interfering amplitudes remain, and we can understand how individual diagrams interfer.
It is clear that the FD gauge allows us to obtain physical amplitudes for each individual Feynman diagram. We do not yet know why this is the case. I would like to explain my own thoughts on the problem, and how it can contribute to the radiative correction frameworks of the SM, QCD and the EW theory.
报告如有变动，请查看：
https://tdli.sjtu.edu.cn/event/4497
11.05
AI + Astronomy: The Development and Application of a New Paradigm
报告人：
Dr. Peng Jia（贾鹏）
时 间：
星期三 2025-11-05 14:00 - 15:00
地 点：
Tsung-Dao Lee Institute/N6F-N601-Meeting Room
Tencent Meeting：
ID: 416683117 (no password)
摘 要：
In recent years, Artificial Intelligence (AI) has been widely applied in astronomical research. A variety of work, characterized by terms such as "large models," "deep learning," and "data-driven" approaches, frequently appears in academic journals and news reports. However, as various AI algorithms are applied to different fields of astronomy, issues such as over-reliance on datasets, unstable results, and poor interpretability have caused astronomical technicians and scientists to gradually raise doubts: Is AI suitable for astronomical research? What are the main obstacles to its practical implementation in astronomy? Considering the development of AI in various sectors and the characteristics of the astronomical discipline, what are the future development directions? This report will draw upon the project team's recent experience in practice and application, combined with several end-to-end AI application cases established by the team, to demonstrate the prospects and development strategies for "AI + Astronomy."
报告如有变动，请查看：
https://tdli.sjtu.edu.cn/event/4528
11.06
Status and Prospects of the RELICS Experiment
报告人：
Dr. Jingqiang Ye（叶靖强）, Status and Prospects of the RELICS Experiment
时 间：
星期四 2025-11-06 11:00 - 12:00
地 点：
Tsung-Dao Lee Institute/N6F-N600-Lecture Room
Tencent Meeting：
https://meeting.tencent.com/dm/ahIvUR1VzYNC
ID: 111342458, Password：123456
摘 要：
Coherent Elastic Neutrino-Nucleus Scattering (CEvNS) is a well-understood Standard Model (SM) process with an enhanced cross section for MeV neutrinos, making it a sensitive probe to beyond-SM physics. A deviation from the prediction indicates beyond-SM physics, such as non-standard interactions, while agreement would further increase our confidence in the SM. The large cross-section also makes CEvNS a promising method of reactor monitoring. The RELICS (REactor neutrino LIquid xenon Coherent Scattering) experiment aims to measure CEvNS using reactor neutrinos with a liquid xenon time projection chamber (LXe TPC). This technology features low threshold, ultra-low backgrounds, and large exposure, which will not only enable measurement of CEvNS but also exploration of new physics signals from reactors. In this talk, I will give an overview of the experiment, present its current status, and discuss its scientific potential.
报告如有变动，请查看：
https://tdli.sjtu.edu.cn/event/4526
编辑：叶丹
责任编辑：张小丽
