⚛️ Particle defied the standard model – new physics may be on the horizon

A muon is a particle with a spin and a negative electric charge. When the muon is affected by a magnetic field, it "wobbles" a certain amount. Something that is called its g-factor. In a recent experiment at Fermilab in Illinois, the researcher's goal was to determine the muons g-factor with as much precision as possible. A contribution to a discussion that has been going on for quite some time.

The result turned out to deviate from what it should be according to the standard model of physics. The scientist calculated the g-factor for the muon to be:  2.00233184122(82).

The first results, that were made public yesterday, may confirm what scientist has hoped for, namely that there are a new fundamental physics to explore beyond the standard model.

“Today is an extraordinary day, long awaited not only by us but by the whole international physics community,” said Graziano Venanzoni, one of the leaders of the experiment in a press conference, quoted by Quanta Magazine.

In the world of small elementary particles, fluctuations can occur so that particles can be sucked up or follow each other. They can also decay into smaller particles. These fluctuations around particles happen more frequently for particles with big mass, and ultimately, it's harder to determine these particles' g-factors. When it comes to muons, nobody has been able to explain why there is a deviation between experiment results and theory.

Blind spots of standard model

Following the Fermilab experiment, the researchers concluded that the muon's aberrant g-factor would occur only in 1 out of 40,000 cases. A large deviation from the theory in other words. But not big enough to single-handedly abandon the standard model. What it is that's causing the muon to behave as it does in the influence of magnetic fields is still unknown. But more experiments and scientific articles on the subject are to be expected.

The standard model has long been the prevailing one in science. However, it still falls short of fully explaining, for example, dark matter or how gravity is working on a quantum mechanical level.
Read more about the study here: First results from Fermilab's Muon g-2 experiment strengthen evidence of new physics | symmetry magazine