时间：2025年5月28日（周三）下午15:00-16:30

Time: 15:00-16:30, Wednesday, May 28, 2025

地点： 西湖大学云谷校区E10-211

Venue: E10-211, Yungu Campus

主持人：西湖大学理学院吴从军讲席教授

Host: Chair Professor Congjun Wu, School of Science, Westlake University

报告语言：中文

Language: Chinese

主讲人/Speaker:

李重生教授，北京大学物理学院

Prof. Chongsheng Li, School of Physics, Peking University

主讲人简介/Biography:

Chongsheng Li was once a professor of theoretical physics at the School of Physics, Peking University. He was a member and an executive member of the Chinese High Energy Physics Society. He won the National Natural Science Award and the Natural Science Award of the Ministry of Education several times.

摘要/Abstract:

In a series of works in 1989, Professor S. Weinberg, and his collaborators discovered that the CP violating operator constructed out of gluon fields (Weinberg Operator) only can contribute to the neutron electric dipole moment (NEDM), and the QCD evolution effect greatly enhances this contribution. By combining with the experimental upper limit of NEDM, S. Weinberg set very strong constraints on the origin of CP violation in particle physics models. This discovery quickly attracted high attention in the international high energy physics community and was once regarded as an important progress in particle physics. We conducted in depth study on this and found that the QCD evolution effect does not enhance but weakens the contribution to NEDM by several orders of magnitude. As a result, the NEDM value given by the above mentioned operator is several orders of magnitude smaller than originally thought. This significantly relaxes the constraints imposed on extensions of the standard model by experimental measurements of NEDM. This conclusion immediately had a strong impact in the international high energy physics community. Professor Weinberg publicly affirmed the correctness of this conclusion and emphasized its citation in his subsequent published papers. Meanwhile, many research groups in the international high energy physics community also independently confirmed this conclusion through calculations. In our subsequent papers, we also proved that the spin matrix extracted from the Weinberg operator satisfies the algebraic relations of the generators of the Lorentz group, thus revealing the physical meaning of the Weinberg operator, that is, it is the color electric dipole moment of the gluon field strength. In this talk, I will, combined with my personal experience, review this period of history and introduce the physical methods and significance of the relevant work.

联系人/Contact:

理学院，朱老师，zhuyi48@westlake.edu.cn

Ms. Zhu, School of Science, zhuyi48@westlake.edu.cn