Research

Research Page Cover

Our research group is dedicated to advancing our understanding of Quantum Chromodynamics (QCD), the fundamental theory describing the strong interaction between quarks and gluons. QCD underlies the structure of hadrons and drives the dynamics observed in high-energy particle collisions at the LHC, RHIC, and other accelerator facilities. Its rich behavior spans a wide range of regimes—from the partonic structure of the proton to the collective phenomena emerging in dense QCD matter—making it one of the central frontiers of modern physics.

By exploring QCD across all energy scales, we address a broad set of fundamental questions: How are the structure, mass, and spin of hadrons generated from quarks and gluons? How do partons evolve, radiate, and form jets in high-energy collisions? How does strongly interacting matter behave in both dilute and high-density environments, from small-x gluon saturation to the quark–gluon plasma? To answer these questions, we develop precision theoretical frameworks for collider physics—including Soft Collinear Effective Theory (SCET) and QCD factorization—and leverage modern computational approaches such as quantum simulation and machine learning to study QCD in both perturbative and non-perturbative domains.

Our work spans nucleon structure, jet physics, gluon saturation, heavy-ion dynamics, and computational approaches to strong-interaction theory. These efforts connect closely with major experimental programs at the LHC and RHIC and are poised to play a central role in interpreting data from the future Electron–Ion Collider (EIC). Our research focuses on the following topics:

Hadron Physics

Confinement

Our main focus along this direction is the quantum imaging of nucleons, specifically understanding the QCD structure of the nucleon and spin physics. QCD, the theory of strong interactions, describes how elementary particles like quarks and gluons interact with each other and is responsible for how quarks and gluons make up hadrons. While the fundamental laws of QCD are elegantly concise, decoding the structural complexity of protons and neutrons in terms of quarks and gluons governed by those laws remains one of the greatest challenges in physics today. This challenge drives the development of cutting-edge experimental facilities.

3D Nucleon Imaging Through QCD factorization theorems, theorists can extract the low-energy properties of nucleon structure from experimental data. In recent years, a multidimensional view of nucleon structure has emerged, offering profound new insights into the internal dynamics of QCD. These advancements address questions such as: How do quarks and gluons move in transverse and longitudinal planes? Do they exhibit orbital motion, contributing to orbital angular momentum? What are the quantum correlations between the motion of partons, their spin, and the spin of the nucleon? This research is closely connected to experimental programs at Jefferson Lab, COMPASS, Belle, RHIC, and the future EIC.

Representative publications include:

QCD Collider Physics

Jets and Colliders

Research in this area focuses on jets, jet substructure, and heavy flavor production, providing valuable insights into QCD dynamics at high energies. By employing perturbative QCD and effective field theory approaches, we study the formation and internal structures of jets originating from quarks and gluons. Collimated jets of hadrons are key observables in high-energy particle interactions, offering a unique window into the partonic structure of the proton and the properties of QCD. Jet substructure measurements, in particular, have become powerful tools for understanding hadronization processes, extracting the strong coupling constant, and probing potential physics beyond the Standard Model (BSM).

Energy-Energy Correlators (EECs) have emerged as a promising theoretical and experimental tool in jet studies. These observables characterize the angular correlations between energy depositions in jets, enabling precise tests of QCD dynamics and allowing for direct comparisons between theoretical predictions and experimental measurements. EECs bridge the gap between perturbative and non-perturbative aspects of jet physics, shedding light on the interplay between parton dynamics and hadronization.

Heavy flavor production, including open heavy flavor mesons and heavy quarkonia, is another central focus. These studies provide critical insights into fragmentation and hadronization mechanisms. Despite decades of research since the discovery of the J/ψ, many aspects of heavy quarkonia production remain challenging to fully understand, making this an ongoing area of investigation. By combining experimental observations with robust theoretical frameworks, our work continues to advance the understanding of QCD dynamics and high-energy phenomena.

Representative publications include:

Gluon Saturation and Heavy Ion Physics

Jet Quenching

Our research explores the extremes of QCD, focusing on gluon saturation and hard scattering in nucleus and heavy ion collisions. Under extreme temperature and density, nuclear matter undergoes a dramatic phase transition into the quark-gluon plasma (QGP), a novel state of matter where quarks and gluons are no longer confined within hadrons. The QGP is believed to have existed a few microseconds after the Big Bang, offering a unique glimpse into the conditions that shaped the early universe. By recreating and studying the QGP in ultra-relativistic heavy ion collisions at RHIC and the LHC, we investigate how strongly interacting matter behaves under such extreme conditions.

Gluons SaturationIn addition to hot nuclear matter, we delve into the enigmatic properties of cold nuclear matter, where partons scatter within dense nuclei. At high parton densities, coherent interactions between gluons lead to a striking phenomenon known as gluon saturation, where the growth of gluon density at small momentum fractions is tamed. This saturation regime is described using the Color Glass Condensate (CGC), a theoretical framework that captures the dynamics of high-density gluonic matter. Understanding gluon saturation not only reveals the underlying dynamics of high-density QCD but also provides crucial insights for interpreting collisions at RHIC, the LHC, and the future EIC.

Representative publications include:

Quantum Computing for QCD

Quantum Computing for QCD

The strong force, as described by QCD, is the most powerful among the fundamental forces, presenting significant computational challenges. Quantum computing and tensor-network methods offer novel approaches to non-perturbative QCD problems—such as real-time dynamics and quantum phase transitions—by enabling controlled simulations of strongly interacting many-body systems. These efforts align with experimental programs at Jefferson Lab, RHIC, the LHC, and the future EIC, paving the way for breakthroughs in high-energy nuclear and particle physics.

Our recent efforts leverage quantum simulation and tensor-network frameworks to address key QCD-related challenges. Examples include simulating chiral phase transitions at finite chemical potential in the Nambu-Jona-Lasinio model (1+1D), exploring real-time dynamics in the Schwinger model (1+1D), and studying parton distributions and dynamics in simplified (1+1D) settings. These exploratory studies provide valuable insights into complex QCD phenomena and complement existing theoretical and computational techniques.

Representative publications include:

Machine Learning in QCD

Machine Learning for QCD

Machine learning is becoming an increasingly important part of our QCD program. We are actively exploring Transformer-based emulators that can reproduce expensive cross-section calculations and approximate solutions to the Balitsky–Kovchegov (BK) equation, providing substantial speedups for global analyses of small-x gluon saturation. In parallel, we are developing Bayesian-inference frameworks for extracting multi-dimensional parton distributions—including TMDs, fragmentation functions, and small-x gluon distributions—where neural-network parametrizations offer the flexibility needed for high-dimensional global fits. We are also pursuing both classical and quantum machine-learning approaches for jet classification, with the aim of improving the identification of quark, gluon, Higgs, and top-quark jets and enhancing the physics reach of collider experiments. These efforts collectively support more precise theoretical predictions and open new opportunities for discovery in high-energy physics.

Representative publications include: