The Muon G minus 2 experiment has reported 4.2 sigma results of an anomaly in the Muons G-Factor. *Pops champaign cork* Woo!

Particle mystery deepens, as physicists confirm that the muon is more magnetic than predicted | Science | AAAS
Ok so WTF?

I’ve read a few different articles on this with varying degrees of boring denseness, and the extra short of why this is important, future theories of quantum electrodynamics potentially have a target to aim for when calculating the Muon’s G-factor, if a new theory doesn’t explain these numbers, then it’s not good enough. Of course it’s not certain yet, it’s only 4.2 sigma, but the experiment has at least one more planned run to go to try and shore that up if it does exist.

A bit more detailed, although to be honest the proper maths of QED gives my head pains, the electron has magnetic moment created by the intrinsic property of spin which causes it to act a bit like a bar magnet with an up and down. The strength of this moment is given by the dirac equation which calculates the multiplying factor ‘g’ of an electron as exactly 2. Throw in some fiddly bits of quantum foam interactions and it’s just a bit higher than 2. Experiments and theory have agreed to amazing precision. Great!

Now we get to the Muon,like an electron but 220 times heavier. That’s no matter though when it comes to it’s magnetic moment, a chunky electron is still the same little bar magnetic and should have the same magnetic moment. The only problem is muons don’t like to stick around and decay quickly, making them quite difficult to study. Hence a giant accelerator ring and it’s massive computer, (the computer systems that log and process the data coming from many of these giant accelerators really deserve credit on their own as engineering marvels.)

An anomaly, or difference between the muon and electron g-factor suggests that the heavier muon is interacting with something that’s giving its spin just a tiny bit more push than it does the electrons. Which sounds unmistakably like potentially related to dark matter to me. Presumably, since an electron isn’t massless, we would see a deviation between theory and experiment with the electron too but it may be so far down to be hidden by noise. There exists another, the Tau lepton, that’s even heavier, but very little study has been done with it and it decays even faster than the muon.

Here is an absurdly large and zoomable image of the experiment, see if you can spot Flash and Reverse-Flash pre transformation.