Why some physicists are skeptical about the muon experiment that hints at "new physics" - Salon

Department of Energy's Fermi National Accelerator Laboratory (Fermilab) in Illinois revealed much-anticipated results from a storied particle physics experiment known as Muon g-2.

The bizarre results, which showed something quite different than what standard theories projected, shocked physicists around the world — and, if confirmed, suggest that fundamental physics theories may be wrong.

The data, published in the journal Physical Review Letters, showed that fundamental particles called muons behaved in a way that was not predicted by the Standard Model of particle physics.

The Standard Model is a gold standard theory that explains the four known forces in the universe and all fundamental particles.

That odd result could be the result of a new, as-yet-undiscovered fundamental particle — which could potentially throw a wrench in everything humans know about physics.

In other words, the Muon g-2 experiment did not reach that golden standard five-sigma bar. .

Despite being one of twelve fundamental particles in the universe, muons are rarely seen; they have properties similar to everyday electrons, in that they hold a charge, yet their mass is far greater than their electron cousins.

It is one of physics' great mysteries that some of the universe's fundamental particles would be so ill-equipped to survive in this universe.

Particle accelerators at Fermilab can produce muons in large quantities, which is what researchers at Fermilab did for the Muon g-2 experiment — tracked how muons interact in a particle accelerator in the presence of a strong magnetic field.

"But when the theorists calculate the same quantity, using all of the known forces and particles in the Standard Model, we don't get the same answer.".

"There is a little bit of skepticism that's been cast on it," Bruce Schumm, a professor of physics at the University of California–Santa Cruz, and the author of a popular book on the Standard Model, told Salon.

"The measurement is intriguing, but its statistical significance of 4.2 standard deviations has not reached the gold standard in particle physics data of 5," Loeb told Salon via email.

Loeb added: "Over the years, many anomalies have cropped up only to disappear, leaving the Standard Model of particle physics unchanged.".

The observed width of the proton, when it was bound with a muon, appeared to be about 4 percent shorter than was expected.  Some physicists speculated that the result could be explained by "new physics" — non-spatial dimensions, new fundamental particles, or something akin.

In other words, if there is a new particle, it is unlikely that the Standard Model will be tossed to the side, but rather built upon.

Caution aside, if the discrepancy is confirmed by future experiments, it could not only change physics but it could further our understanding of the universe — and perhaps even explain inexplicable phenomena like dark matter, which may be related to undiscovered particles. .