Scientific Research

Research Field

Research

My recent research focuses on high-energy theory, in particular, the non-perturbative QCD, hadron structure and computational physics. You can check out my published work, recent talks and developements.

Here are some information for beginners.

Physical background

The quantum chromodynamics (QCD) describes the interactions between quarks and gluons. It is strong coupling at low-enegy scale, which leads to remarkable non-perturbative physics, e.g. confinement and chiral symmetry breaking. 企业微信截图_16282178057253.png

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 Nuclear Physics, such as how the quarks and gluons are binding 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 12 GeV upgrade of CEBAF at Jefferson Lab, the electron-ion collider (eRHIC) at Brookheaven National Lab, both in United States, the LHCb & ALICE experiments at CERN in Europe, the electron ion collider of China (EicC) at HIAF in Huizhou, the BESIII experiment at BEPC in Beijing, as well as the Belle II experiment at KEK in Japan.

The Hamiltonian formalism is one of the fundamental theoretical frameworks of quantum theory and is widely used in physics. This formulation is non-perturbative and provides access to information at the amplitude level as well as the real-time evolution information, through the Schrödinger equation. The Hamiltonian formalism has been a standard tool in addressing strong coupling quantum many-body systems, such as the nuclei, atoms as well as the molecules. 企业微信截图_16282178291993.png The light-front dynamics, proposed by Paul Dirac, exploits dynamical evolution in the light-front time. It brings several dramatic simplification to the relativistic dynamics. Thus the light-front Hamiltonian formalism is a natural framework for describing hadrons as relativistic bound states. It is non-perturbative and provides direct access to the hadronic observables in Richard Feynman's parton picture, one of the modern pillars in high-energy scattering experiments.

Recent advances in computational sciences (including quantum computing) provide opportunities to compute the non-perturbative solutions of QCD from first principles. Of course, the unique challenges posed by QCD require significant efforts in both the computational front and the physical front, separately and joinly, which are what I try to address in my research.

Basis light-front quantization

Basis light-front quantization (BLFQ) is a numerical framework to solve light-front QCD as quantum many-body problems. It is inspired by the recent development in ab initio nuclear structure calculations. BLFQ is designed to preserve all kinematically symmetries of the Hamiltonian and exploits the sparse matrix technologies to accelerate the quantum many-body calculations. 企业微信截图_16282178528672.png

The starting point of BLFQ is an effective Hamiltonian defined in a designated model space. To obtain the effective Hamiltonian, one can start from the canonical QCD Hamiltonian at high-energy scales and obtain the bound-state effective Hamiltonian from the Hamiltonian renormalization group method, as is demonstrated in quantum electrodynamics (QED).

Alternatively, one can employ phenomenological effective interactions at low-energy scale. We proposed a model based on confining interactions from light-front holography and a one-gluon exchange interaction. We use the model to investigate the meson spectroscopy. The obtained light-front wave functions can be used to access hadronic observables and parton distributions.

Fock sector dependent renormalization

Non-perturbative renormalization is one of the fundamental challenges in quantum field theory (QFT) at strong coupling. The challenge is amplified in the Hamiltonian formulation of QFT, as explicit covariance is lost there. Remarkably, cluster decomposition still holds in light-front dynamics, even though all diagrams are strictly light-front time ordered. This fact is exploited in the Fock sector dependent renormalization (FSDR) to enable non-perturbative renormalization in light-front field theories with systematic Fock sector truncations. FSDR has been successfully applied to (3+1)d QFTs, including scalar Yukawa theory, Yukawa theory and QED, with exact cancellations of ultraviolet divergences. The scalar Yukawa theory in particular is computed up to a Fock sector of 3 dressing particles and a good Fock sector convergence is achieved for form factors.

Other interests

QCD at finite temperature
Quantum many-body theory & quantum computing
Low-energy nuclear physics
Advanced algorithms in computational physics
Foundations of quantum mechanics

非微扰光锥方法研究强子的力学性质,

Talks

Conferences

Light front holography with chiral symmetry breaking: a quest for a semiclassical approximation to QCD. 轻味矢量介子理论与实验联合研讨会. July 19-23, 2021, Xining, Qinghai. Invited Talk.
Basis Light-Front Quantization Approach to meson spectrum and structures. ILCAC Wednesday Seminars. March 3, 2021 (online). Invited Talk.
Quarkonium as a relativistic bound state on the light cone. 2017 Fall Meeting of the American Physical Society, Dvision of Nuclear Physics (DNP 2017), Oct. 25-28, 2017, Pittsburgh, Pennsylvannia, U.S. Invited Talk.
Basis Light-Front Quantization Approach to Heavy Quarkonium. Baryons 2016, May 16-20, 2016, Tallahassee, Florida, U.S.
Heavy Quarkonia on the Light Front. APS April Meeting 2016, April 16-19, 2016, Salt Lake City, Utah, U.S.
Heavy quarkonium in a light-front holographic basis. Light Cone 2016 (LC2016), Sep. 5-8, 2016, Lisbon, Portugal. Invited Talk.
Quarkonium in a Holographic Basis. 2015 Fall Meeting of the APS Division of Nuclear Physics (DNP2015), Oct. 28-31, 2015, Santa Fe, New Mexico, U.S.
Quarkonium in a holographic basis. XXVIII Midwest Theory Get-Together (MWTGT), Sep. 11-12, 2015, Argonne National Lab, Illinois, U.S.
Scalar Yukawa Model on the Light Front: ab initio approach to quantum field theory. APS April meeting 2015, Apr. 11-14, Baltimore, Maryland, U.S.
Non-Perturbative Calculation of Scalar Yukawa Theory in Light-Front Dynamics. Light Cone 2014 (LC2014), May 26-30, 2014, Raleigh, North Carolina, U.S. Invited Talk.
Convergence of the Fock Sector Expansion in Light-Front Hamiltonian Field Theory. XXVII Midwest Theory Get-Together (MWTGT), Sep. 5-6, 2014, Argonne National Lab, Illinois, U.S.
Introduction to basis light-front quantization approach to QCD bound state problem. International Conference on Nuclear Theory in the Supercomputing Era (NTSE 2013), May 13-17, 2013, Ames, Iowa, U.S. Invited Talk.
A Novel Basis for Light-Front Quantum Field Theory. XXV Midwest Theory Get-Together (MWTGT), Sep. 7-8, 2012, Argonne National Lab, Illinois, U.S.
Calculation of BLFQ Hamiltonian Matrix Elements. XXIV Midwest Theory Get-Together (MWTGT), Sep. 23-24, 2011, Argonne National Lab, Illinois, U.S.

Seminars

Light front holography with chiral symmetry breaking: from semiclassical approximation to ab initio QCD. Particle and Nuclear Physics Seminar, June 4, 2021, University of Science and Technology of China, Hefei.
物质基本结构与超级计算机. Guest Lecture on the Undergraduate Research Program, Nov. 20, 2020, University of Chinese Academy of Sciences, Beijing.
Electrodynamics of dual superconducting medium. Institute of Modern Physics, Chinese Academy of Sciences, January 4, 2018, Lanzhou, China.
Quarkonium on the light front. Theory Center Cake Seminar, November 8, 2017, Jefferson Lab, Virginia, U.S.
Non-Perturbative Quantum Field Theories on the Light Front. Guest Lectures given at PHYS 625: Physics of Strong Interactions, Iowa State University, August 22 & 24, 2017, Ames, Iowa, U.S.

Yang Li

ZipCode:
PostalAddress:
Email: