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International research team reproduces the magnetic properties of the muon with the highest accuracy
For more than 50 years, the Standard Model of particle physics has formed the basis of our understanding of nature at the smallest scale. It describes the behavior of elementary particles under the influence of the fundamental forces of nature.
Using modern supercomputers, an international research team has demonstrated that the Standard Model also correctly describes the magnetic properties of muons. Dr. habil. Davide Giusti, who conducts research at the University of Regensburg and the Jülich Supercomputing Center, together with the rest of the team, was able to push the boundaries of supercomputing with unprecedented precision and demonstrate that the Standard Model can explain the value of the muon’s anomalous magnetic moment measured in experiments.
The muon was discovered as early as 1936 and is a heavier “relative” of the electron. It is produced, among other things, when cosmic rays hit the Earth’s atmosphere. In fact, hundreds of muons pass through our bodies every minute. Due to their magnetic properties, muons are particularly sensitive test objects for fundamental laws of nature.
Since the 1960s, a series of increasingly precise experiments at major international research centers such as CERN, Brookhaven National Laboratory, and the Fermi National Accelerator Laboratory (Fermilab) have measured its magnetic moment with exceptional accuracy. This decades-long achievement in experimental research was recently honored with the prestigious 2026 Breakthrough Prize in Fundamental Physics. For many years, small but persistent discrepancies emerged between measurements and theoretical predictions—a finding that presented physics with a fundamental puzzle.
This apparent discrepancy long fueled hopes for new, previously unknown physics. It was only through a decisive breakthrough in theory that the puzzle could now be solved. The key lies in an extremely precise calculation of the so-called hadronic vacuum polarization—one of the most complex and, until now, most uncertain contributions to the theory. Using an innovative hybrid approach that combines powerful lattice calculations with selected, well-understood experimental data, the team succeeded in significantly reducing the uncertainty.
The calculations were performed on supercomputers. The accuracy achieved is extraordinary: it is comparable to trying to identify a single ant across a distance of more than 100 soccer fields lined up end to end. This was made possible by fine four-dimensional grids, improved computational methods, and the intelligent combination of various theoretical approaches.
The result is a milestone: the new prediction of the Standard Model agrees with the latest experimental measurements of the muon’s magnetic moment to within 0.5 standard deviations. This confirms the Standard Model in this particularly demanding test—to an impressive precision of eleven decimal digits.
This breakthrough was made possible by the use of modern supercomputers. These are high-performance computers consisting of hundreds of thousands to millions of computing units working simultaneously and capable of processing extremely complex tasks in parallel. In this study, these computers were used to numerically solve the equations of the Standard Model by dividing space and time into a very fine lattice. Only with this enormous computing power can the tiny quantum effects of the strong interaction be measured with the necessary precision. Supercomputers are therefore an indispensable key technology for conducting the most precise tests of fundamental laws of nature.
This work underscores not only the power of modern supercomputers but also the strength of quantum field theory methods as a whole.
The results were published in “Nature”.
Dr. habil. Davide Giusti
Fakultät für Physik, Universität Regensburg
Jülich Supercomputing Centre, Forschungszentrum Jülich
E-mail: davide.giusti@ur.de I d.giusti@fz-juelich.de
https://doi.org/10.1038/s41586-026-10449-z
Artistic representation of a myon
Copyright: Peter and Ryan Allen and University Wuppertal
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Artistic representation of a myon
Copyright: Peter and Ryan Allen and University Wuppertal
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