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Congratulations! SJTU Team Shares Prestigious International Science Award

May 06, 2026 Page views: 1015

Recently, the 2026 Breakthrough Prize in Fundamental Physics was announced, with the international Muon g-2 Collaboration—spanning three generations of experiments at CERN, Brookhaven National Laboratory, and Fermilab—named among the laureates. The prize is one of the three major categories of the Breakthrough Prize, carrying a cash award of USD 3 million for each category, and is widely known as the “Oscars of Science.”

Among them, the Fermilab Muon g-2 Collaboration played a particularly important role among the three generations of experiments recognized by the prize. Based on its final measurement results released in 2025, the collaboration advanced the experimental precision of the muon anomalous magnetic moment to 127 ppb, delivering the latest and most precise experimental result to date. As one of the core contributing teams of the Fermilab Muon g-2 Collaboration, the muon physics team at Shanghai Jiao Tong University shared this top international honor in fundamental physics with 376 researchers worldwide.

Awardees from the Muon Physics Team at Shanghai Jiao Tong University

Award-Winning Achievement

The muon anomalous magnetic moment experiment is one of the most iconic precision measurement experiments in international particle physics over the past six decades. The muon is often described as the electron’s “heavier sibling,” with a mass approximately 207 times that of the electron. Like the electron, the muon behaves as a tiny magnet, precessing around its spin axis in an external magnetic field at a rate described by the “g factor.” Quantum field theory predicts that virtual particles constantly emerging and annihilating in the vacuum cause the value of g to be slightly greater than 2. This tiny “anomaly” makes the muon an exceptionally sensitive probe for potential new particles and new interactions beyond the Standard Model of particle physics. The muon anomalous magnetic moment experiment aims to measure this anomalous deviation, aμ = (g − 2)/2, with unprecedented precision. This precision measurement not only helps test the completeness of quantum field theory and the Standard Model, but also opens new pathways for exploring physics beyond the Standard Model.

The Breakthrough Prize in Fundamental Physics specifically recognized the landmark contributions made by three generations of Muon g-2 collaborations to the field of particle physics. CERN made the first meaningful measurement of the anomalous magnetic moment in the 1960s and 1970s; Brookhaven National Laboratory significantly improved the measurement precision in the 1990s; and Fermilab transported the 15-meter-diameter, 50-ton superconducting storage-ring magnet to the western suburbs of Chicago in 2013 by sea and land, ultimately advancing the experimental precision to 127 ppb, or 127 parts per billion. This represents an approximately 30,000-fold improvement over the precision achieved in CERN’s first experiment in 1965, making it one of the most precise fundamental physics measurements in the world.

The citation for the Breakthrough Prize also stated: “The prize recognizes the pioneering work of three generations of collaborations over several decades in measuring the muon anomalous magnetic moment, continuously pushing the limits of experimental precision and opening a new era in the search for new physics beyond the Standard Model.”

Measuring the Distance Between Beijing and Shanghai with an Error No Greater Than the Width of a Hand

The 60-Year Journey Behind 127 ppb

127 ppb represents the latest and most precise experimental result to date. But what exactly does it mean?

“It is like measuring the distance from Shanghai to Beijing with a margin of error no greater than the width of a human palm,” explained Xu Jinxiang, Associate Professor at the Tsung-Dao Lee Institute of Shanghai Jiao Tong University.

Why invest such enormous effort in pursuing an accuracy down to “the width of a hand”? “It is like taking a photo of the Moon with a mobile phone: when the resolution is not high enough, all you can see is a blurry point of light; as the resolution improves, the outline of the Moon begins to emerge; and when the resolution is pushed to the extreme, every detail of the craters becomes clearly visible,” the research team explained. The higher the precision, the more underlying physical phenomena scientists are able to observe. Three of the four fundamental forces of nature — the electromagnetic, strong and weak forces — all leave detectable imprints on the muon’s magnetic moment. Only by first calculating the contributions of these three known forces with great clarity, and then combining them with experiments of extreme precision, can this probe cut through the fog and reveal deeper hidden laws of the microscopic world.

Each extension of our line of sight into the microscopic universe is the result of a long journey carried forward by generations of scientists. Breakthroughs in fundamental science are often built upon this decades-long persistence in pushing the limits of what is possible.

Conducting Experiments Like Opening a “Blind Box”:
What Is This “Probe” Searching For?

To understand this physics breakthrough, we must first get to know a unique player in the microscopic universe: the muon.

As an indivisible fundamental particle in nature, the muon is often regarded as the electron’s “heavier sibling.” It behaves like an extremely tiny magnet. When placed in an external magnetic field, its spin axis rotates around the direction of the magnetic field like a tilted spinning top — a motion known as “precession.” Quantum field theory predicts that virtual particles constantly emerging and annihilating in the vacuum produce tiny additional corrections to the muon’s magnetic moment. This slight deviation beyond the classical prediction is what scientists call the “anomalous magnetic moment.”

Why have scientists spent decades pursuing this tiny value with such persistence? Professor Li Liang from the School of Physics and Astronomy at Shanghai Jiao Tong University offered an answer: “It is not only an ultimate test of existing theories, but also a gateway to the unknown world of new physics.” The Standard Model of particle physics describes the fundamental particles and interactions we currently know. If nature still hides undiscovered new particles or entirely new forces, they could subtly affect the muon’s magnetic moment, causing the final experimental result to deviate from theoretical predictions. For this reason, the muon has become an extremely sensitive “quantum probe” of the microscopic world.

“We obtain the muon anomalous magnetic moment in two ways: first, by calculating its magnetic strength with extremely high precision through theory; and second, by measuring it with extremely high precision through experiment.” Only by pushing both theoretical calculations and experimental measurements to their limits, and then placing the two side by side for comparison, can scientists determine whether existing theories perfectly describe the microscopic world.

Interestingly, the experiment was like a meticulously designed “blind-box opening” game. To prevent researchers from unconsciously aligning the results with theoretical expectations, the collaboration adopted a rigorous “blind analysis” approach.

During data processing, an unknown offset is deliberately added to the results. “We do not know what the true result is. Only after we have ruled out all kinds of errors from every possible angle and are confident that there is no problem with the data analysis do we open this ‘blind box,’” Xu Jinxiang said candidly. Until the very last moment, neither the theoretical nor the experimental teams can access the true number. They do not begin with a predetermined answer. “Whether the results agree or not, they will expand the boundaries of human knowledge.”

Previously, the muon anomalous magnetic moment experiment was selected twice as one of Science magazine’s Top 10 Breakthroughs of the Year, in 2021 and 2025.

As a Founding Member Institution, SJTU Team Fully Participates in the Research Mission

Shanghai Jiao Tong University officially joined the Fermilab Muon g-2 Collaboration in 2012 as a founding member institution. It is one of the research institutions within the collaboration with the most comprehensive involvement in experimental measurement tasks. Led jointly by Professor Li Liang from the School of Physics and Astronomy and Associate Professor Xu Jinxiang from the Tsung-Dao Lee Institute, the SJTU team has made a series of important contributions in areas including the reconstruction and analysis of the muon anomalous precession frequency, high-precision magnetic field measurement and calibration, beam dynamics corrections, modeling of coherent beam oscillations, and performance studies of electromagnetic calorimeters and silicon photomultiplier readout systems.

Group Photo of the Muon Physics Team at Shanghai Jiao Tong University’s School of Physics and Astronomy (2026)

Li Liang led the team to join the Fermilab Muon g-2 Collaboration in 2012 and is one of the principal leaders of the Muon Physics Team at Shanghai Jiao Tong University. Over the years, he has guided the team in deeply participating in key tasks, including detector development, high-precision magnetic field measurement and calibration, offline data processing, and data analysis, making important contributions to the experiment’s achievement of a world-leading measurement precision of 127 ppb. During the detector development stage, Professor Li Liang was deeply involved in the development of the calorimeter system, carried out tests on lead fluoride crystals, and participated multiple times in beam tests of calorimeter prototypes, laying an important foundation for calorimeter performance optimization and high-precision measurements. Professor Li has served as secretary of the collaboration and was twice elected to its Executive Committee. Since 2018, he has continuously served as the overall coordinator of the collaboration’s Offline Data Group, taking full responsibility for experimental data production, transmission, preprocessing, reconstruction and simulation. He also organized the development of the core offline framework that supports data processing and physics analysis for the entire experiment. To address experimental challenges such as complex pileup backgrounds and energy gain effects, he led the team in developing data-driven correction methods and high-precision detector simulation algorithms, effectively reducing systematic uncertainties and improving the precision of signal extraction. As the principal PI of the SJTU team, he has also been deeply involved in and led core analyses, including the measurement of the muon precession frequency and precise magnetic field measurement and calibration. The independent analysis results produced by the SJTU team were incorporated into the collaboration’s final combined measurement results. Among more than 30 institutions in the international collaboration, the SJTU team ranks among the leading contributors in both scale and impact, fully demonstrating its important academic influence in international scientific collaboration.

In addition, Professor Li Liang is also a core member of the ATLAS team at Shanghai Jiao Tong University. He has made important contributions to frontier research areas including precision measurements of the top quark, searches for new physics, searches for double Higgs production, and measurements of the Higgs self-coupling. As a member of both the ATLAS Collaboration and the Fermilab Muon g-2 Collaboration, Professor Li shared the Breakthrough Prize in Fundamental Physics in 2025 and 2026 respectively, an experience that is extremely rare in the global scientific community. Professor Li has also actively promoted the extension of international frontier research achievements in muon physics to major scientific infrastructure in China. He has led the development of the DREAMuS experimental program based on the High Intensity Heavy-ion Accelerator Facility, or HIAF, and participated in the founding of the Muon Beam Working Group of the Chinese Particle Accelerator Society, where he serves as deputy head. These efforts have made important contributions to the development of China’s muon science research platforms and the growth of its research community.

Group Photo of the Shanghai Jiao Tong University Muon Physics Team at the Tsung-Dao Lee Institute (2025)

Xu Jinxiang joined the Muon g-2 Collaboration in 2015 and has successively served as co-convener of the muon anomalous precession frequency analysis group and as a member of the collaboration’s Executive Committee. He is one of the few scientists in the collaboration to have been deeply involved throughout the entire chain of work, from experimental design, R&D, construction, commissioning and data acquisition to the publication of the final physics results. In the early stage, he systematically carried out studies on muon beam injection and storage. During the detector development phase, as a core member of the beam-test and performance studies for the PbF₂ electromagnetic calorimeter and SiPM readout system, he helped lay the calibration-method foundation for high-precision energy and time reconstruction of positrons from muon decay, and developed the corresponding software and algorithm framework. During the commissioning stage, he led the construction of the Nearline system, providing the experiment with a fast data channel for event reconstruction. In 2019, Xu Jinxiang joined the Tsung-Dao Lee Institute as a “Tsung-Dao Lee Fellow” and soon led his newly established research team in taking on key tasks within the collaboration, including the Phase Acceptance beam dynamics systematic correction working group, where he served as co-leader, and the beam Betatron oscillation systematic uncertainty analysis working group, where he served as leader. During this work, he innovatively developed a non-parametric coherent betatron oscillation, or CBO, modeling method based on Gaussian process regression. This effectively overcame the precision bottleneck of traditional parametric fitting in beam dynamics corrections and provided important methodological support for systematic uncertainty estimation in the Run 4/5/6 data analysis stage.

In addition, Xu Jinxiang has led his team in joining the muon electric dipole moment experiment, or muEDM, at the Paul Scherrer Institute in Switzerland as an initial member and collaborating institution. He has successively served as simulation and analysis coordinator and muon detector coordinator for the experiment. With support from the Shanghai Municipal Science and Technology Commission’s “Special Zone for Basic Research” program, he has also collaborated with Shanghai Tech University and the Chinese Academy of Sciences Shanghai Advanced Research Institute to advance preliminary research on a muon source based on SHINE. With support from the Shanghai Municipal Bureau of Planning and Natural Resources, he has worked with Shanghai Geology and Mineral Resources Group and other institutions to expand research on muon imaging applications for underground spaces in megacities. Xu Jinxiang is currently a member of the Muon Beam Working Group under the Particle Accelerator Branch of the Chinese Physical Society. He was awarded the 2026 Shanghai Jiao Tong University President’s Award, and will serve as chair of the Local Organizing Committee for NuFact 2026, the International Workshop on Neutrino Factories, to be held this August.

Group Photo of the Shanghai Jiao Tong University Muon Physics Team at the First International Workshop on High-Luminosity and High-Precision Frontier Muon Physics (MIP 2023)

The Shanghai Jiao Tong University Muon Physics Team has carried out extensive collaboration and joint training with leading international research institutions, including Fermilab, Argonne National Laboratory, the University of Washington, Cornell University, Boston University, the University of Illinois, Michigan State University, the National Institute for Nuclear Physics in Italy, Johannes Gutenberg University Mainz in Germany, the University of Manchester and the University of Liverpool in the United Kingdom, and the High Energy Accelerator Research Organization in Japan. The team hosted the first International Workshop on High-Luminosity and High-Precision Frontier Muon Physics, or MIP 2023, in 2023, and the inaugural China-Japan-Europe Muon Physics Workshop in 2025. This year, it will host NuFact 2026, the International Workshop on Neutrino Factories. The team’s related research has received strong support from the National Natural Science Foundation of China, the Key Laboratory for Particle Astrophysics and Cosmology of the Ministry of Education, the School of Physics and Astronomy at Shanghai Jiao Tong University, and the Tsung-Dao Lee Institute. The team would like to express its sincere gratitude for their support.

Congratulations to the award-winning team!

Strengthening basic research and building China into a leading nation in science and technology.

SJTUers, let us move forward together with united efforts and achieve even greater success!