Non-perturbative QCD Group

Welcome to the NpQCD Group at USTC

Strong Interaction, Hadronic Structure and Computational Physics

Exploring physics at the heart of matter

Research

Quantum chromodynamics (QCD) is the underlying theory of Strong Interaction. It describes the interactions between quarks and gluons. QCD is strongly coupled at low-enegy scale, which leads to remarkable non-perturbative physics, e.g. confinement and chiral symmetry breaking. The non-perturbative calculation of QCD is one of the most formidable challenges in Physics. It is also the key to answer some of the fundamental questions in Physics, such as how the quarks and gluons are bound together, and how the nuclear forces are formed to bind the nucleons. The non-perturbative properties of hadrons is also the focii of some present and forthcoming high-energy experiments, such as the electron-ion colliders (EICs) and the Super Tau-Charm Facilities (STCFs). For a comprehensive yet readable introduction to QCD, we recommend the following review: F. Gross and E. Klempt et. al., 50 Years of Quantum Chromodynamics, Eur. Phys. J. C 83, 1125 (2023).

The research of our group delves into the heart of the visible matter, the structures of the hadrons, such as the proton. We aim to understand how the non-perturbative structures of hadrons emerge from the quarks and gluons. To tackle these challenging issues, we employ a combination of theory, phenomenology and computation. One of our favorite approaches is the light-front Hamiltonian formalism. In this approach, the structures of the hadrons are fully described by the wave functions defined at on the light front \(x^+ \equiv ct+z = 0\). It is also closely related to the partonic structures of hadrons. Our ultimate goal is to develop an ab initio computational framework to solve for the light-front wave functions directly from the QCD Hamiltonian. For a review of light-front QCD, see Section 5.3 of the above review 50 years of QCD.

Specific topics of our group include:

Our Team

Yang Li

Yang Li is a professor of physics at the University of Science and Technology of China (USTC). He graduated from USTC in 2010. He obtained his Ph.D. at Iowa State University in 2015 under Prof. James Vary. He then worked at Iowa State University, the College of William & Mary and the University of the Chinese Academy of Sciences as postdocs and a lecturer. In 2021, he joined USTC as a professor. His primary research interests are Particle and High-Energy Nuclear Physics including non-perturbative QCD and hadronic structures. He received Gary McCartor Award by the International Light Cone Advisory Committee (ILCAC) in 2014. See his homepage and his inspire page for more information.

Contact: leeyoung1987\(@\)ustc.edu.cn

Bheemsehan Gurjar

Bheemsehan Gurjar is a postdoctoral researcher at the University of Science and Technology of China. He received his Ph.D. in 2024 from the Indian Institute of Technology Kanpur (IIT Kanpur). His research focuses on the three-dimensional structure of hadrons, aiming to deeply explore the quark-gluon dynamics inside the proton through QCD phenomenology. He has visited Jefferson Lab (JLab), North Carolina State University, and the Instituto Tecnológico de Aeronáutica (ITA) in Brazil. In 2023, he was awarded the Gary McCartor Award for Young Scientists by the International Light-Cone Advisory Committee (ILCAC).

Contact: gbheem\(@\)ustc.edu.cn

Xianghui Cao

Xianghui Cao is a graduate student at University of Science and Technology of China (USTC). He graduated from USTC in 2022 and subsequently joined Prof. Yang Li’s group. His research interests are non-perturbative quantum field theory and hadron physics.

Contact: xianghuicao\(@\)mail.ustc.edu.cn

Wenyu Zhang

Wenyu Zhang is a graduate student at University of Science and Technology of China (USTC). He graduated from USTC in 2024 and joined Prof. Yang Li's group. His research interests are non-perturbative quantum field theory, hadron physics and computational physics.

Contact: zwy_2020\(@\)mail.ustc.edu.cn

Qi'ao Li

Qi'ao Li is a graduate student at University of Science and Technologu of China (USTC). He is expected to graduate in 2025 and join Prof. Yang Li's group. His interests are particle physics and non-perturbative QCD.

Contact: frontal\(@\)mail.ustc.edu.cn

Yiyang Chen

Yiyang is an undergraduate student at the University of Science and Technology of China, expected to graduate in 2026 and join Professor Li Yang's research group. His research interests are in non-perturbative QCD.

Contact: cyy342106557\(@\)mail.ustc.edu.cn

Xin Zhang

Xin Zhang is an sophmore at the University of Science and Technology of China. His research interests are QFT in strong external fields.

Recent Visitors

  • Tobias Frederico, Professor at Instituto Tecnologico de Aeronautica, Brazil
  • J. Pacheco B.C. de Melo, Professor at the Laboratório de Física Teórica e Computacional - Universidade Cruzeiro do Sul, Brazil
  • Yiyu Zhou, Postdoctoral Research at Turin University, Italy
  • Qintao Song, Associate Professor at Zhengzhou University
  • Wenyang Qian, Postdoctoral Researcher at University of Santiago de Compostela, Spain
  • Meijian Li, Postdoctoral Researcher at University of Santiago de Compostela, Spain
  • Xingbo Zhao, Researcher at Institute of Modern Physics, Chinese Academy of Sciences
  • Guangyao Chen, Assistant Professor at Jacksonville University
  • Mengyao Huang, Postdoctoral Researcher at Lawrence Livermore National Laboratory
  • James Vary, Distinguished Professor at Iowa State University
  • Kamil Serafin, Postdoc at Institute of Modern Physics (present affiliation: Tufts University)
  • Weijie Du, Postdoc at Iowa State University

Alumni

  • Yihan Duan, Master Diploma (-> Pittsburgh U)
  • Zhiguo Wang, Master（-> Hefei Ion）
  • Liuyuan Wen, Master（-> Nanjing U）
  • Tianyang Hu, undergraduate (-> Institute of Modern Physics)
  • Jialin Chen, undergraduate at Lanzhou University (-> Institute of Modern Physics)

Publications

Journal Articles (since 2021)

  1. Xianghui Cao, Bheemsehan Gurjar, Chandan Mondal, Chen Chen, and Yang Li*, Origin of the nucleon gravitational form factor $B_N(t)$, [arXiv: 2601.19141 [hep-ph]]
  2. Wenyu Zhang, Wenyang Qian, Yiyu Zhou, Yang Li*, and Qun Wang, Quantum entanglement between partons in a strongly coupled quantum field theory, [arXiv: 2512.21228 [hep-ph]]
  3. Xianghui Cao, Yang Li*, Chao Shi, James P. Vary, and Qun Wang, Convergence in charmonium structure: light-front wave functions from basis light-front quantization and Dyson-Schwinger equations Phys. Rev. D 113, 014028 (2026); [arXiv: 2507.17330 [hep-ph]]
  4. Liuyuan Wen, Meijian Li, Yiyu Zhou, Yang Li*, James P. Vary, Relativistic dynamics of charmonia in strong magnetic fields, Phys. Rev. D 112, 014019 (2025); [arXiv: 2504.03294 [hep-ph]]
  5. Wenyu Zhang, Yang Li*, James P. Vary, Covariant analysis of electromagnetic current on the light cone: exposition with scalar Yukawa theory, JHEP 07, 194 (2025); [arXiv: 2501.07826 [hep-ph]]
  6. Siqi Xu*, Yiping Liu, Chandan Mondal, Jiangshan Lan, Xingbo Zhao, Yang Li, James P. Vary, Towards a first principles light-front Hamiltonian for the nucleon, Phys. Lett. B 867, 139599 (2025); [arXiv: 2408.11298 [hep-ph]]
  7. Tianyang Hu, Xianghui Cao, Siqi Xu, Yang Li*, Xingbo Zhao, James P. Vary, Gravitational form factor D of charmonium from shear stress, Phys. Rev. D 111, 074031 (2025); [arXiv: 2408.09689 [hep-ph]]
  8. Xianghui Cao, Yang Li*, James P. Vary, Dissecting a strongly coupled scalar nucleon, Phys. Rev. D 110, 076025 (2024); [arXiv: 2408.09535 [hep-ph]]
  9. Lingdi Meng, Shuo Tang, Zhi Hu*, Guo-Li Wang, Yang Li, Xingbo Zhao, James P. Vary, Electron form factors in Basis Light-front Quantization, [arXiv: 2405.16995 [hep-ph]]
  10. Yi Chen, Yang Li, Cédric Lorcé*, Qun Wang, The nucleon axial radius, Phys. Rev. D 110 (2024) 9, L091503; [arXiv: 2405.12943 [hep-ph]]
  11. Xianghui Cao, Siqi Xu, Yang Li*, Guangyao Chen, Xingbo Zhao, V.A. Karmanov, James P. Vary, Energy momentum tensor on and off the light cone, JHEP 07 (2024) 095; [arXiv: 2405.06896 [hep-ph]]
  12. Yang Li*, Qun Wang, James P. Vary, Hadronic energy-momentum tensor revisited, [arXiv: 2405.06892 [hep-ph]]
  13. Yihan Duan, Siqi Xu, Shan Cheng, Xingbo Zhao, Yang Li*, James P. Vary, Flavor asymmetry from the non-perturbative nucleon sea, Phys. Rev. C 110, 065201 (2024); [arXiv:2404.07755 [hep-ph]]
  14. Siqi Xu, Xianghui Cao, Tianyang Hu, Yang Li*, Xingbo Zhao, James P. Vary, Stress out of charmonia, Phys.Rev.D 109 (2024) 11, 114024; [arXiv: 2404.06259 [hep-ph]]
  15. Yang Li*, James Vary, Stress inside the pion in holographic light-front QCD, Phys. Rev. D 109, L051501 (2024); [arXiv:2312.02543 [hep-th]]
  16. Zhiguo Wang, Meijian Li*, Yang Li, James P. Vary, Shedding light on charmonium, Phys. Rev. D 109, L031902 (2024); [arXiv:2312.02604 [hep-ph]]
  17. Siqi Xu*, Chandan Mondal, Xingbo Zhao, Yang Li and James P. Vary, Quark and gluon spin and orbital angular momentum in the proton, Phys. Rev. D 108, 094002 (2023); [arXiv: 2209.08584 [hep-ph]]
  18. Xianghui Cao, Yang Li*, James Vary, Forces inside a strongly-coupled scalar nucleon, Phys. Rev. D 108, 056026 (2023); [arXiv: 2308.06812 [hep-ph]]
  19. Yang Li*, Wen-bo Dong, Yi-liang Yin, Qun Wang, James P. Vary, Minkowski's lost legacy and hadron electromagnetism, Phys. Lett. B 838 (2023) 137676; [arXiv: 2206.12903 [hep-ph]]
  20. Yang Li*, P. Maris, and J.P. Vary, Chiral sum rule on the light front, Phys. Lett. B 836 (2023) 137598; [arXiv: 2203.14447 [hep-th]]
  21. Yang Li*, and J.P. Vary, Longitudinal dynamics for mesons on the light cone, Phys. Rev. D 105, 114006 (2022); [arXiv: 2202.05581 [hep-ph]]
  22. Yang Li, Meijian Li*, and J.P. Vary, Two-photon transitions of charmonia on the light front, Phys. Rev. D 105 (2022) 7, L071901; [arXiv: 2111.14178 [hep-ph]]
  23. Meijian Li, Yang Li*, Guangyao Chen, T. Lappi, and J.P. Vary, Light-front wavefunctions of mesons by design, Eur. Phys. J. C 82 (2022) 11; [arXiv: 2111.07087 [hep-ph]]
  24. Siqi Xu* et al. (BLFQ Collaboration), Nucleon structure from basis light-front quantization, Phys. Rev. D 104 (2021) 9, 094036; [arXiv: 2108.03909 [hep-ph]]
  25. Yang Li*, and J.P. Vary, Light-front holography with chiral symmetry breaking, Phys. Lett. B 825 (2022) 136860; [arXiv:2103.09993 [hep-ph]]
* Corresponding authors

Reviews and Chapters

  1. James P. Vary, Chandan Mondal, Siqi Xu, Xingbo Zhao, and Yang Li, Nucleon Structure from Basis Light-Front Quantization : Status and Prospects, Eur. Phys. J. Spec. Top. (2025), [arXiv: 2512.08283 [hep-ph]]
  2. James P. Vary, Yang Li, Chandan Mondal and Xingbo Zhao, Light-front quantization, in 50 Years of Quantum Chromodynamics, F. Gross and E. Klempt Eds., Eur. Phys. J. C 83, 1125 (2023)

Talks

Conferences

Seminars

Events