The E989 collaboration has recently published the most precise measurement of the muon anomalous magnetic moment $a_\mu$ with an uncertainty of $0.46\,\mathrm{ppm}$.
The new experimental world average of $a_\mu$ deviates by 4.2 standard deviations from the Standard Model prediction provided by the Muon g-2 Theory Initiative. Emerging results from ab-initio lattice QCD calculations for hadron-physics contributions allow to scrutinize this tantalizing hint for physics beyond the Standard Model for the first time in a three way comparison.
To extract the value of $a_\mu$ a frequency comparison experiment is performed with spin-polarized muons confined in a superbly controlled electric and magnetic field environment.
A measurement of the difference between the Larmor and the cyclotron frequency, the so-called anomalous spin precession frequency, is combined with a high-precision measurement of the magnetic field environment which is performed using nuclear magnetic resonance techniques.
I discussed the most recent result of the Fermilab Muon g-2 experiment's first physics data run performed in 2018.
I reported on the experimental improvements implemented for the subsequent science runs that will allow the collaboration to achieve the ultimate goal of $0.14\,\mathrm{ppm}$ uncertainty on $a_\mu$.