https://apod.nasa.gov/apod/ap210413.html

In 2001, f Brookhaven National Laboratory indicated that the Standard Model of Particle Physics, adopted widely in physics, is incomplete. Specifically, the muon, a particle with similarities to a heavy electron, has had its relatively large wobble under scrutiny in a series of experiments known as g-2 (gee-minus-two).

Reporting in last week, the most sensitive muon wobble experiment yet, conducted at Fermi National Accelerator Laboratory (Fermilab) in Illinois and pictured here, agreed with the Brookhaven result. The unexpected wobble rate may indicate that an ever-present sea of virtual particles includes types not currently known. Alternatively, it may indicate that flaws exist in difficult theoretical prediction calculations.

Technical info at https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.126.141801 “Measurement of the Positive Muon Anomalous Magnetic Moment to 0.46 ppm”. The result is 3.3 standard deviations greater than the standard model prediction and is in excellent agreement with the previous Brookhaven National Laboratory (BNL) E821 measurement. Combining the two experiments together gives 4.2 standard deviations.

Image of Fermilab