物理学院 School of Physics, Nanjing University

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【2013年10月】Prospects for the physics of cold, sparse hadrons

2014年05月04日

我们组邀请了

1) 美国阿贡国家实验室(Argonne National Laboratory)理论部主任、国际著名非微扰场论专家 C. D. Roberts 教授来访问交流,并作“钟山论坛”报告。

标题:Prospects for the physics of cold, sparse hadrons

时间:10月16日、18日及20日上午9:30

地点:物理楼233

Abstract: Almost all the Universe's visible matter is comprised from nucleons and the nuclei they constitute; but even after a century of striking progress in subatomic physics, an intimate understanding of these principal building blocks is still lacking. The problem resides in quantum chromodynamics (QCD), the Standard Model (SM) component that describes interactions between quarks and gluons, and hence is supposed to explain nucleon and nuclear structure. The properties of this theory are some of Nature's best kept secrets. QCD presents science with a unique problem: never before have we faced a theory whose elementary degrees-of-freedom are not those readily accessible via experiment; i.e., whose basic quanta are confined, by forces stronger than any previously encountered. The problem of solving QCD is the purview of Hadron Physics, which is an international research endeavor of remarkable scope. Indeed, before the end of this decade, the field will be operating a host of upgraded or new facilities and detectors. This presentation will describe some of the opportunities and challenges presented by the next decade -- with an upgrade at Jefferson Lab, fixed target experiments at FermiLab and worldwide discussions about an electron ion collider -- as an international community attempts to solve the essentially nonperturbative problem posed by QCD, and uncover the origin of 98% of the visible mass in the Universe.


2)肯特州立大学(Kent State University)前副校长、国际著名非微扰场论专家 P. C. Tandy 教授来访问交流,并作报告。

标题:Hadron Physics from the DSEs of QCD

时间:10月15日下午3点、17日及19日上午9:30

地点:物理楼233

Abstract: A) Introductory Overview: Important features of QCD, path integrals in QFT, non-perturbative continuum QFT methods, what are DSEs, why use DSEs, truncations of DSEs, role of Ward Takahashi Identities, etc. For hadron physics, what are we trying to do, and why are we trying to do it? B) Hadrons & Form Factors: Using the pion as our typical hadron, the usage of DSEs is illustrated for the elastic and transition form factors of the pion, linking the soft infrared region with the hard ultraviolet region where there are long-standing theoretical predictions from asymptotic QCD. That is, what is going on inside the pion, and do we understand it over the distance scales accessible to experiment, and what is the prediction for new experiments to be done at JLab within the next 5 years? How are calculations actually carried out? The pion is also atypical in some respects and there might be time for some comments about the “vacuum” quark condensate. Some comments can be made about progress in explaining and predicting the form factors of other hadrons if time permits. C) The Parton Structure of Hadrons: The concept of a parton in a hadron originates from the simplification of the theoretical description of very high scattering processes when a hadron is viewed in the light-front frame or the “infinite momentum” frame. I will again use the pion as the typical hadron to illustrate the use of DSEs to explain the pion’s parton distribution amplitude (m this DA is the light-front projection of its Bethe-Salpeter wave function). I will then show how DSEs provide insight into the pion and kaon parton distribution functions (these PDFs are measured by Deep Inelastic Scattering (DIS) of leptons upon hadrons, or by the Drell-Yan process of hadron—antihadron scattering). How are calculations actually carried out?

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信息来源:宗红石

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