Date & Time: 14:00 PM, May 16 (Friday), 2025

Host: Prof. Jianda Wu

Venue: TDLI Meeting Room N601

Tencent Meeting link: 

https://meeting.tencent.com/dm/b0tEo7lKnLS4Meeting ID: 470155139, no password

Abstract:

Symmetry distills the simplicity of natural laws from the complexity of physical phenomena. The perspective of high symmetries bridges large-spin cold fermion systems with high energy physics. For example, a generic SO (5), or, isomorphically Sp(4) symmetry is proved in spin-3/2 systems. Moreover, an exact SO (7) symmetry is identified, which exhibits an extraordinarily uni-fying power. Its χ-pairing operator extends Yang’s η-pairing to a high-rank Lie algebra, integrat-ing 21 orders in both particle-hole and particle-particle channels into a unified framework. Such systems also exhibit multi-fermion orderings, including quartetting superfluidity (charge 4e) and quartet density wave, which are α-particle-like, or baryon-like orderings. The resonant quantum plaquette states of SU (4) antiferromagnetism are described by a high-order gauge theory. A G2 symmetric Hubbard model with spin-3/2 fermions is constructed lying in the intersection between SO (7) algebras connected by the structure constants of octonions. The G2 symmetry can be spon-taneously broken into either an SU (3) one, or, into an SU (2) ×U (1). In the quantum disordered states, quantum fluctuations generate effective SU (3) and SU (2) ×U (1) gauge theories for low energy fermions. 

References:

1.  Zhi-Qiang Gao, C. Wu, J. High Energ. Phys. 2025, 202 (2025) .

2.  Zhiqiang Gao, Congjun Wu, arXiv:2010.14126 .

3.  C. Wu, Mod. Phys. Lett. B 20, 1707 (2006) (brief review). 

4.  C. Wu, Phys. Rev. Lett. 95, 266404 (2005).

5.  C. Wu, J. P. Hu, and S. C. Zhang, Phys. Rev. Lett. 91, 186402 (2003).

Biography:

Congjun Wu received his Ph.D. in physics from Stanford University in 2005 and did his postdoc-toral research at the Kavli Institute for Theoretical Physics, University of California, Santa Bar-bara, from 2005 to 2007. He became an Assistant Professor in the Department of Physics at the University of California, San Diego in 2007, an Associate Professor in 2011, and a professor in 2017. In 2021, he became a Chair Professor at School of Science, Westlake University.  He was selected as a New Cornerstone Investigator in 2023, elected to a Fellow of American Physical Society in 2018, and awarded the Sloan Research fellowship in 2008. His research interests are exploring new states of matter and revealing their organizing principles, including quantum magnetism, superconductivity, topological states, mathematical physics, and the numerical meth-od of quantum Monte Carlo simulations.