The Muon Anomalous Magnetic Moment (g − 2)
Problem statement
The measured muon anomaly $a_\mu = (g-2)/2$ has differed from some Standard Model predictions at the few-sigma level,
$$\Delta a_\mu = a_\mu^{\text{exp}} - a_\mu^{\text{SM}} \neq 0?$$
Is the tension a signal of new physics, or an artifact of hadronic vacuum-polarization uncertainties? Lattice-QCD and data-driven estimates currently disagree.
Claims (1)
The tension in muon g-2 likely arises from the discrepancy between dispersive and Lattice-QCD HVP evaluations. Reconciling them requires consistency with the global electroweak fit, specifically the hadronic contribution to the running of the fine-structure constant.
BMW Collaboration (2021)
Discussion (3)
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Beautiful formulation — do you expect the bound to be tight?