A new force of nature? Scientists are approaching a fifth force when they discover a mysterious subatomic particle that disobeys the laws of physics
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Scientists are getting closer to identifying a new force of nature after observing the peculiar ‘wobble’ of a subatomic particle.
The experts whizzed tiny muons, resembling electrons, through a ring 50 feet in diameter in the U.S. Department of Energy’s Fermilab in Batavia, Illinois.
Measurements of the muon’s magnetic ‘wobble’ can’t be explained by the Standard Model of particle physics — possibly indicative of an unknown particle or force.
Because muons are formed naturally when cosmic rays hit Earth’s atmosphere, these results could change how we think the universe works.
The findings support previous findings from 2021, but comprise more than four times the amount of data analyzed, reinforcing the “new physics” claim.
The Muon g-2 ring is located in the detector hall of the United States Department of Energy’s Fermi National Accelerator Laboratory (Fermilab) in Batavia, Illinois
Fermilab scientists have described their work in detail a research paper filed Thursday in the journal Physical Review Letters.
“We’re looking for an indication that the muon is interacting with something we don’t know about,” said study co-author Brendan Casey, a senior scientist at Fermilab.
“It could be anything – new particles, new forces, new dimensions, new features of space-time, anything.”
Casey theorizes that the results indicate a “new property of space-time” or a violation of Lorentz invariance, a principle that states that the laws of physics are the same everywhere.
“That would be insane and revolutionary,” he said.
For centuries, scientists have tried to figure out what happens at the “subatomic” level, with particles smaller than atoms.
Atoms, the basic units of matter that we can see and touch, combine to form molecules (which in turn form solids, gases, and liquids).
Physicists describe how the universe works at this fundamental subatomic level with a theory known as the Standard Model, developed in the early 1970s.
It suggests that everything in the universe is made of a few basic building blocks called fundamental particles, which are controlled by four forces: the strong force, the weak force, the electromagnetic force, and gravity.
The muons, which resemble electrons, circulate thousands of times at nearly the speed of light in an attempt to measure how they ‘wobble’ over time
Called the Muon g-2 experiment, as the particles traveled along the 15-meter-long magnetic track, they wobbled 0.1 percent from the standard model that’s been used for 50 years.
Over the course of the 20th century, it became established as a time-tested physical theory and has accurately predicted a wide variety of phenomena.
However, the model fails to explain some of the deepest mysteries in modern physics, including what dark matter is made of and the imbalance of matter and antimatter in the universe.
To help solve some of these mysteries, researchers have been looking for particles that behave in different ways than would be expected in the Standard Model.
The recent experiments at Fermilab, referred to as Muon g-2, studied the wobbling of muons as they traveled through a magnetic field.
The muon (pronounced mew-on) is a magnetically negatively charged particle similar to its cousin the electron, but 200 times heavier.
They form naturally when cosmic rays hit the Earth’s atmosphere.
Importantly, muons are also magnetic and wobble as they spin in the presence of a powerful magnetic field.
The muon, like the electron, has a small internal magnet that causes it to wobble—or, technically, “precess”—like the axis of a spinning top.
It measures ‘magnetic moment’ – the degree of the object’s tendency to align with a magnetic field
The Fermilab experiment — conducted at unthinkably cold temperatures of -268 °C (-450 °F) — shot jets of muons into the doughnut-shaped superconducting magnetic storage ring 15 meters (50 feet) in diameter.
The muons circulate thousands of times in the ring at nearly the speed of light in an attempt to measure how they “wobble” over time.
As the muons zip around, they interact with other subatomic particles that, like little “dance partners,” change their wobble.
Detectors along the ring allowed scientists to determine how quickly the muons “precessed.”
Similar to the 2021 results, the speed of the wobble, as measured in the experiment, varied significantly from what had been predicted from the Standard Model.
The muon’s “magnetic moment”—the measure of the object’s tendency to align with a magnetic field—as a function of the particle’s spin is represented by the letter g, and should be slightly larger, according to theory. are then 2.
However, the newly announced measurements showed that the magnetic moment is about 0.2 parts per million stronger, a small but significant amount.
The new effort replicates and improves on an earlier experiment at Brookhaven National Laboratory in New York, whose 2006 results were the first to suggest that the muon’s behavior differed from the Standard Model.
Subsequent measurements at Fermilab reinforced this result with more certainty, but no more than the new results.
The 2021 results also showed an abnormal fluctuation, but the new results were based on a quadrupling of the amount of data, strengthening confidence in the findings.
The new effort replicates and improves on an earlier experiment at Brookhaven National Laboratory in New York, whose 2006 results were the first to suggest that the muon’s behavior differed from the Standard Model. The subsequent measurements at Fermilab reinforced this result with more certainty
The team is still working on integrating three more years of data for a final measurement of the muon’s so-called “magnetic moment.”
Ultimately, the findings continue to point to a mysterious factor at play — possibly “unknown particles or forces” that could rival the significance of the 2012 discovery of the Higgs boson.
“With all this new knowledge, the result is still consistent with previous results and this is hugely exciting,” said study co-author Dr Rebecca Chislett from University College London.
The results further reinforce our team’s previous accurate measurements of the muon’s anomalous magnetic moment, achieving unprecedented accuracy in testing the Standard Model and deeper into the subatomic world.”