The Muon wobble (v1.0)

Key reference is Marcela Carina in Scientific American.

Muons are much heavier than an electron to which family it belongs (about 200 times heavier). A Muon behaves similar to an electron and can be thought of as a much heavier version of an electron. The extra mass makes them better probes for new phenomena in high-precision laboratories because any deviations from their expected behavior will be more noticeable. Muons are produced in abundance by cosmic rays in Earth’s atmosphere; more than 10,000 of them pass through our bodies every minute. 

In a heavy magnetic field though muon's spin wobbles. This wobble is influenced by virtual particles that keep appearing and disappearing in empty space around it according to the rules of quantum mechanics. If there are additional particles in the universe beyond the ones we know about, they, too, will show up as virtual particles and exert an influence on a muon’s wobble in our experiments. A 2001 experiment gave tantalizing hints of the muon wobble. The Muon G-2 results just published by Fermilab is much more accurate and not only confirms it but shows that the wobble deviates from what is predicted by theory, given the particles we know of today in the standard model of particle physics. Final results will be published in 2025 and will be even more accurate. This possibly implies there is one or more unknown virtual particles or forces (a force is also treated as a particle), influencing the muon wobble that goes beyond the standard model. With the evidence from these two experiments, we are now very near the rigorous statistical threshold physicists require to claim a “discovery.” - the 5-sigma threshold (about a one-in-a-million chance that the findings are just a result of random variations). 

A new particle (force or matter) has not been experimentally confirmed since the Higgs Boson in 2012 (it was predicted decades earlier in 1964 by Peter Higgs). So, this is incredibly exciting to physicists. It may unveil the identity of dark matter (85% of unknown matter in the universe) or even a new force. Or a new quirk of space-time itself? or do theorists just have to correct their calculated numbers to fix errors, so the discrepancy disappears? Either way, there's something that's not understood, and it needs to be resolved. 

Physicists find incredibly creative ways to probe into the unknown. Who would have ever thought a teeny-weeny wobble in a Muon would possibly point to a new particle?