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More than two decades of research on a project led by a �Ը������� University professor has resulted in a new discovery in nuclear physics that is being celebrated nationally. 

The breakthrough came from work done by Brookhaven National Laboratory’s STAR Collaboration, an international group of hundreds of scientists and engineers who conduct nuclear research using the laboratory’s Solenoidal Tracker at RHIC (STAR) detector at the . 

Zhangbu Xu, Ph.D., �Ը������� physics professor in the College of Sciences and Humanities, is the leader of this specific project that resulted in an important discovery about the role of gluons, the glue-like particles that hold quarks together inside protons, within high-energy particle collisions. 

, which was published on Aug. 13 by the STAR Collaboration, is featured in the prestigious journal Science. The study explores the most powerful force in the universe that is confined to the nuclei inside atoms and invisible to the eye yet is responsible for 99% of the mass of the visible universe.   

Unlocking the Structure of Protons 

Since the 1970s, scientists have used a theory known as Quantum Chromodynamics to identify this force. In the past, theories held that the quantum number is assigned to just three quarks inside the protons. However, the team’s research shows that the protons are more complicated than just three quarks, with a Y-shaped gluon structure, dubbed a baryon junction, inside the protons. 

The implications of the discovery extend beyond nuclear physics, Xu said. The baryon junction concept is also relevant to future experiments at the Electron-Ion Collider, currently under development at Brookhaven National Laboratory, where scientists aim to map the 3D structure of protons and neutrons with unprecedented precision. �Ը������� joined the Electron-Ion Collider international collaboration in 2024. 

Making a Big Bang in Research 

Xu, who joined the �Ը������� faculty in 2024, has spent his entire career researching high-energy nuclear physics. His work connects �Ը������� to groundbreaking projects that explore the conditions of the universe just moments after the Big Bang. 

The work is based at the U.S. Department of Energy’s Brookhaven National Laboratory in Upton, New York, where Xu served as spokesperson for the STAR Collaboration from 2014-2017 and as co-spokesperson from 2017-2020.  

“We conduct experiments and analyze scientific data as a team,” he said. “I lead the research project, but it is a collaborative effort. The detector we use, the operation, the data collection and various essential calibrations at the facility are all performed collectively by the collaboration.” 

Xu received his doctoral degree at Yale University in 1999 and then spent two years at Yale as a postdoctoral researcher before joining Brookhaven National Laboratory in 2001. After more than two decades there, Xu said teaching was his next frontier. 

“I had been in the national lab for 23 years,” he said. “But teaching was something I had never done before and something I wanted to try.” 

Xu chose �Ը������� because he had worked with �Ը������� physics faculty and students for more than 20 years through the collaboration. When a faculty position in the Department of Physics became open, Xu said he was immediately interested. 

“I knew the professors and many students here,” he said. “The faculty and students from �Ը������� that I have worked with for the past 20 years have all been very high quality.” 

Xu also maintains a joint appointment at Brookhaven National Laboratory. 

Collaborating and Discovering 

�Ը������� has been part of the STAR Collaboration since its inception, through its High-Energy Nuclear Experiment Group, which for many years was led by now-retired Professor Declan Keane, Ph.D., along with other faculty and student researchers, including Chun Yuen “Tommy” Tsang, Ph.D., a former postdoctoral researcher at �Ը������� and one of the authors of the research findings.  

Tsang joined the team in 2023 and quickly became the corresponding author who not only deals with a specific data analysis presented in the paper but also assesses systematic uncertainties for other analyses, standardizes the analysis code, edits paper drafts and is in charge of the communications between the collaboration team and the journal editor, Xu said. 

“Clearly, one of the reasons I came here is because the group at �Ը������� has a very strong background in nuclear research and is quite well known both for theory and experiments,” Tsang said about joining �Ը�������. Tsang took a postdoctoral position at Argonne National Laboratory in March 2026. He continues to work on projects related to the STAR experiment and the Electron-Ion Collider.  

According to information from Brookhaven National Laboratory, “the Solenoidal Tracker at RHIC, known as STAR, tracks the thousands of particles produced by ion collisions at RHIC. STAR is used to search for signatures of the form of matter that RHIC was designed to create: the quark-gluon plasma (QGP). Detecting and understanding the QGP allows for a better understanding of the universe in the moments after the Big Bang, where the symmetries (and lack of symmetries) of our surroundings were put into motion.” 

�Ը������� Holds Prestigious R1 Research Designation 

Since 2022, �Ը������� has been recognized with an R1 designation by the Carnegie Classification of Institutions of Higher Education, which denotes top research universities in the nation. The classification is a testament to �Ը�������’s commitment to excellence in research, innovation and scholarship. 

The R1 designation is the highest level of research activity for doctoral universities, putting �Ը������� among an elite group of institutions known for their significant contributions to research and development and the training of doctoral students. Only 187 universities in the nation have R1 status, placing �Ը������� in the top 5% of institutions with respect to research activity. 

Learn about �Ը�������’s Department of Physics.