Muon’s magnetic moment in physics: Another stunning experiment you should know about
A groundbreaking discovery in the realm of physics is on the horizon, yet conclusive evidence remains to be seen.
A minute particle’s peculiar wobble could potentially unmask an unprecedented fifth force of nature, according to experts involved in one of the most prominent particle physics experiments.
The team at the Fermi National Accelerator Laboratory, fondly known as Fermilab, situated near Chicago, has stumbled upon compelling indicators suggesting the muon, a minute subatomic entity, is displaying more wobble than theoretically anticipated — possibly due to the influence of an unidentified force.
This observation builds upon an experiment conducted in 2021, boasting quadruple the data, with a halved margin of error. If validated, these observations could mark a monumental shift in the realm of physics, rivaling breakthroughs dating back half a century when prevailing theories of subatomic particles were established.
In essence, the subtle gyration of the muon — referred to as its magnetic signature — might challenge foundational scientific principles.
Brendan Casey, a lead scientist at Fermilab involved in the Muon g-2 experiment, expressed, “We’re really probing new territory. We’re determining the muon magnetic moment at a better precision than it has ever been seen before.”
Commonly dubbed “fat electrons,” muons bear resemblance to electrons but possess 200 times the mass and are inherently unstable, transforming into electrons and minuscule, intangible particles called neutrinos within moments. An intrinsic quality called spin makes them resemble miniature magnets, inducing gyration when subjected to magnetic fields.
To scrutinize this gyration, Fermilab’s physicists had muons circling within a supercooled magnetic loop, almost at light speed — a velocity that extends the fleeting lifespan of muons due to the effects of time dilation.
After monitoring the muons’ trajectories across the 50-foot-wide loop, the team inferred the muon’s wobble exceeded expectations.
Researchers suggest this anomaly might be due to factors not recognized by the Standard Model — the foundational equations defining all subatomic entities, unchanged since the 1970s.
This elusive element might be an entirely new force (beyond the recognized gravitational, electromagnetic, and nuclear forces). Or perhaps it’s an exotic particle, an additional dimension, or an unexplored facet of space-time.
Whichever interpretation is accurate, it’s evident that an unknown entity is influencing the muons within the loop.
Absolute verification is still pending. The complete dataset from the 2018-2023 g-2 experiment is under scrutiny, currently analyzing 2019-2020 findings. Concurrently, scientists await the Standard Model’s predictive updates.
Presently, two theoretical techniques estimate the muon’s expected wobble under the Standard Model, yielding divergent results. Some recent calculations even challenge the groundbreaking implications of the 2021 g-2 experiment’s outcomes.
Parallel research from the CMD-3 accelerator in Novosibirsk, Russia, indicates normal muon wobble, conflicting with prior accelerator tests.
With the comprehensive results anticipated in 2025, Fermilab’s team is optimistic about attaining clarity.
The researchers have presented their findings for consideration in the journal “Physical Review Letters”. An early version of the study is available for review here.
Image Credit: Mark Lopez/Argonne National Laboratory