Fermilab Scientists Nearing Discovery of Fifth Force of Nature

In 2021, Fermilab researchers announced the first results from the Muon g-2 experiment, which accelerates fundamental particles called muons in a giant toroidal magnet (above). Muons have negative charges like electrons but are about 200 times as massive. When particles with both charge and spin get close to the speed of light, as in the g-2 particle accelerator, we can detect how fast they gyrate. That’s called the “g-factor.”

The Standard Model says muons should have a g-factor of 2. In 2021, Fermilab said muons have anomalous g-factors slightly less than 2 that the Standard Model cannot explain. Scientists have speculated that the Muon g-2 experiment is detecting a new fundamental force. We currently know of four: gravity, electromagnetism, the strong nuclear force (nuclear cohesion), and the weak nuclear force (radioactive decay). The discovery of a fifth could rewrite physics…