Vietnamese scientists advance to core roles in world's largest particle physics experiments

In a basement laboratory in Hanoi, a team of physicists is helping to answer one of the universe's most stubborn riddles: why anything exists at all. They are part of a collaboration that stretches across continents and involves more than a thousand scientists, all working on two of the world's most sophisticated particle physics experiments—Belle II and T2K—both located in Japan. The work, which runs through 2026, represents a turning point for Vietnamese science: these researchers are no longer assisting from the margins. They are now responsible for core technical operations that directly shape what the experiments can discover.

The shift is significant enough to warrant attention. For years, Vietnamese scientists participated in international physics collaborations by learning from more established partners or handling data after the fact. Now, under the leadership of Dr. Nguyen Anh Ky from the Vietnam Academy of Science and Technology's Institute of Physics, they have moved into positions where their work is foundational. At Belle II, the Vietnamese team—including Dr. Dong Van Thanh from Hanoi University of Science and Technology—contributed to building, installing, testing, and calibrating the central drift chamber, one of the experiment's most critical components. This device tracks the paths and momentum of charged particles created when electrons and positrons collide at nearly the speed of light. The team now operates and maintains several detector systems, ensuring the precision that makes Belle II's data reliable.

Belle II itself is hunting for an answer to a profound asymmetry in nature. When the universe began, theory suggests that matter and antimatter should have been created in equal amounts, annihilating each other completely and leaving nothing behind. Yet here we are—galaxies, stars, planets, life. Something tipped the balance. The SuperKEKB accelerator that powers Belle II has set world records for how frequently it can smash particles together, making it one of the most advanced machines of its kind. The Vietnamese contribution helps ensure that when collisions happen, the experiment captures what occurs with the precision needed to understand why the universe did not simply vanish.

The T2K experiment, where Vietnamese scientists also hold critical roles, pursues a different mystery: the nature of neutrinos. These are among the most elusive particles known—ghostly things with almost no mass that pass through ordinary matter as if it were not there. Billions stream through your body every second without leaving a trace. T2K generates a beam of neutrinos by firing high-energy protons at a target, then watches as those neutrinos travel 295 kilometers underground to a detector called Super-Kamiokande, buried roughly a thousand meters beneath the earth's surface. The experiment is designed to observe neutrino oscillation—the phenomenon in which one type of neutrino transforms into another during its long journey. This transformation proves that neutrinos have mass, a discovery that contradicted the Standard Model of physics and opened new questions about the universe's composition.

Associate Professor Nguyen Thi Hong Van and Dr. Cao Van Son lead the Vietnamese contribution to T2K. Their team operates the neutrino beam accelerator and manages the near-detector systems that monitor the beam immediately after it is created. This upstream work is not peripheral. The measurements they take determine what the far detector should expect to see, allowing scientists 295 kilometers away to calculate how many neutrinos should arrive and how they have changed along the way. Dr. Ky emphasized the weight of this responsibility: few research groups from other countries are trusted with such a position. The Vietnamese team's work directly affects the operation and scientific outcomes of the entire experiment.

What makes this advancement meaningful extends beyond the physics itself. High-energy physics has implications for nuclear physics, astrophysics, cosmology, electronics, and materials science. More immediately, participation in cutting-edge international experiments allows Vietnamese researchers to acquire knowledge and technical expertise that can be applied at home. International collaboration also distributes costs—something crucial for a developing nation's research budget. Yet Dr. Ky stressed that sustained progress requires sustained funding. High-energy physics demands long-term investment, often spanning decades. He called for funding mechanisms lasting at least five years per cycle to support the development of Vietnam's fundamental research workforce and enable long-term scientific planning.

The work has already borne fruit in publication. Professor Nguyen Quang Liem, chairman of the evaluation council at the Vietnam Academy of Science and Technology, noted that the project exceeded its original targets in both the quantity and quality of papers published in leading international journals. This matters because it signals that Vietnamese science is not just participating in global research—it is contributing discoveries that the world's scientific community recognizes and builds upon. The question now is whether Vietnam's government and institutions will sustain the investment needed to keep these researchers at the table as the experiments continue and new ones begin.