Physicists are continuously striving for new theories to deepen our understanding of the universe, particularly to address fundamental questions that remain unanswered.
A significant challenge arises in the search for undiscovered forces and particles: how to identify them without prior knowledge of their characteristics.
Take dark matter, for instance. Despite observing its effects throughout the cosmos, the nature of this enigmatic entity remains elusive. To comprehend dark matter, physicists believe new physics will be essential.
Recently, a groundbreaking experimental result, coupled with new theoretical calculations, has emerged, potentially shedding light on this new physics and offering inquiries into the nature of dark matter.
### Exploring the Muon
At the center of this promising development is the muon—an elementary particle akin to an electron but with a significantly greater mass.
Muons originate from cosmic rays, which are high-energy particles colliding with Earth’s atmosphere. Remarkably, about 50 muons traverse your body every second.
Their exceptional ability to penetrate solid objects more effectively than x-rays makes muons valuable tools in uncovering hidden structures. They have been deployed in various fascinating applications, such as detecting concealed chambers in ancient pyramids, assessing magma chambers in volcanoes to forecast eruptions, and examining the interior of the Fukushima nuclear reactor post-meltdown.
### A Subtle Gap in Physics
In 2006, researchers from Brookhaven National Laboratory achieved an extraordinarily precise measurement of the muon’s magnetism, accurate to around six parts in ten billion. To put this in perspective, that’s like determining the weight of a fully loaded freight train to within ten grams.
This measurement was compared against rigorous theoretical calculations, leading to a surprising discovery: a slight but significant discrepancy between the two figures. This incongruity raised the tantalizing possibility of unearthing new physics.
### An Enhanced Experiment
In pursuit of a conclusive answer, the scientific community launched a 20-year initiative to improve the accuracy of both experimental and theoretical assessments.
Funding and resources were mobilized to transport the massive electromagnet from the original experiment to Fermilab in Chicago, where it underwent a complete renovation for a fresh round of measurements.
Researchers recently announced the conclusion of this experiment, reporting a measurement for the muon’s magnetism that boasts an impressive 4.4-fold increase in precision, now standing at one-and-a-half parts in ten billion.
### Upgraded Theoretical Insights
Simultaneously, the theoretical side had to advance significantly. The Muon g-2 Theory Initiative, composed of over 100 scientists, was formed to refine predictions regarding the muon’s magnetism.
The team meticulously calculated contributions from over 10,000 factors, even incorporating insights from the Higgs boson, discovered back in 2012. However, the most significant hurdle lay in analyzing the effects of the strong nuclear force, one of the four fundamental forces in the universe—an endeavor fraught with complexity.
### Bridging Gaps with Antimatter
In 2020, the Theory Initiative directed its focus toward electron-positron collisions, harnessing measurements from these interactions to provide the necessary missing pieces for their computations.
When combined with other contributions, these findings produced a result that more than sufficiently conflicted with the latest experimental findings—hinting at the potential existence of new physics.
At that time, I pursued a different methodological avenue alongside my colleagues from the Budapest-Marseille-Wuppertal collaboration.
We conducted simulation studies using supercomputers to model the strong nuclear contribution. Our results mitigated the previously existing disparity between theory and experiment. However, a new perplexity arose concerning the longstanding discrepancies in the electron-positron collision data, which had been rigorously validated by two decades of research.
### Disappearing Hints and New Questions
As more research progressed, two additional teams produced simulations aligning with our outcomes. Following further refinements, our updated simulation was released as a preliminary report, pending peer review, achieving nearly double the precision of previous work.
To ensure the results remained unbiased, the simulations were executed using a method called
image source from：https://theconversation.com/how-physicists-used-antimatter-supercomputers-and-giant-magnets-to-solve-a-20-year-old-mystery-257891
