The recent measurement of the magnetic moment of the muon [1] has a quoted discrepancy of ~4 sigma from the Standard Model prediction. Not surprisingly, this has generated a lot of popular interest (eg, [2]), and will probably generate a flurry of theoretical explanations.

In this informal seminar, we will present the motivation for muon g-2 experiments, and discuss the techniques used in the recent measurement. We will then give an understandable summary of the difficulties involved in the QCD calculations that go into the Standard Model prediction, and compare the two main approaches that have been used [3,4].

We will leave plenty of time for audience comments and discussions about the meaning of this result.

== References ==

1. Measurement of the Positive Muon Anomalous Magnetic Moment to 0.46 ppm
   B Abi et al., Phys. Rev. Lett. 126, 141801 (2021)
   
2. 'Last hope' experiment finds evidence for unknown particles, Quanta Magazine, www.quantamagazine.org/muon-g-2-experiment-at-fermilab-finds-hint-of-new-particles-20210407/
   
3. The anomalous magnetic moment of the muon in the Standard Model
   T Aoyama et al., Phys. Reports 887, 1 (2020)
   
4. Leading hadronic contribution to the muon magnetic moment from lattice QCD
   S Borsanyi et al., Nature, Apr 7 (2021), arXiv:2002.12347