News Release

Thermodynamics of heavy quarkonium in a Bayesian holographic QCD model

Probing the dissociation process of heavy quarkonium in the QGP medium

Peer-Reviewed Publication

Nuclear Science and Techniques

Bound state of heavy quarkonium without the QGP medium.

image: 

Heavy quarkonium is a bound state formed by a heavy quark and its corresponding antiquark of the same flavor under the strong interaction, such as the J/ψ particle, which consists of a charm quark and an anticharm quark, known as charmonium. With relatively large masses, heavy quarkonia are produced during the initial hard scattering processes in heavy-ion collisions—prior to the formation of the QGP medium. As a result, when heavy quarkonia traverse the QGP medium, they carry information about the QGP, making them ideal probes for investigating the properties of the medium. In relativistic heavy-ion collisions, when J/ψ particles pass through the QGP medium, the color screening effect of the medium causes the bound state to dissociate, resulting in free charm quarks and anticharm quarks.

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Credit: Zhou Kai

Dissociation of Heavy Quarkonium
Under the guidance of Professor Kai Zhou, the research team conducted an in-depth exploration of the thermodynamic properties and dissociation mechanisms of heavy quarkonium in relativistic heavy-ion collisions. Heavy quarkonium is a bound state formed by a pair of heavy quarks and antiquarks through strong interactions mediated by gluons. During heavy-ion collisions, when heavy quarkonium traverses the QGP medium, it is affected by the color screening effect of the medium, leading to its dissociation.

Investigating the Dissociation Process Using Theoretical Models:
To gain a deeper understanding of the dissociation process of heavy quarkonium, the research team primarily employed the EMD model combined with Bayesian analysis to thoroughly investigate the influence of temperature and chemical potential on the thermodynamic properties and dissociation behavior of heavy quarkonium. A systematic analysis was conducted on how temperature and chemical potential affect key thermodynamic quantities, including the dissociation distance, potential energy, entropy, entropy force, binding energy, and internal energy of heavy quarkonium, thereby revealing its deconfinement mechanism. This work has enabled the academic community to achieve a more profound understanding of the dissociation behavior of heavy quarkonium as it traverses the QGP medium. Professor Kai Zhou noted, "Our research methodology has significantly enhanced the explanatory power regarding how heavy quarkonium is affected by color screening effects in the QGP medium, providing a more precise theoretical description for understanding its dissociation behavior."

Implications for Science
This study not only expands the theoretical understanding of heavy-ion collision physics and the phase structure of quantum chromodynamics (QCD) matter, but also deepens the comprehension of QGP properties under extreme conditions. It establishes a new theoretical framework for exploring the behavior of QCD matter in high-energy-density environments.

Advancing Research in High-Energy Nuclear Physics
Building on these findings, the research team is now shifting its focus to more complex dynamic scenarios. Future studies will center on the effects of dynamically evolving temperature and chemical potential on the dissociation process of heavy quarkonium, aiming to better approximate the physical conditions of real heavy-ion collision environments and thereby promote the systematic refinement of theoretical models in high-energy nuclear physics.

"By deeply integrating holographic QCD theory with Bayesian analysis, we have transformed the dissociation mechanism of heavy quarkonium from theoretical deduction into a physical image that can be precisely calculated and verified," stated Professor Kai Zhou. "This work not only deepens the understanding of quark dynamics in the QGP medium but also builds a bridge connecting microscopic QCD behavior with macroscopic experimental observations. Each theoretical advancement provides new perspectives for revealing the properties of extreme nuclear matter and injects new possibilities into the design of future high-energy physics experiments and the development of related technologies."

The complete study is via by DOI: https://doi.org/10.1007/s41365-026-01903-8


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