The Muon Magnetic Moment as a Vacuum Ledger: Polarisation Entries From Electrons to Hadrons

The anomalous magnetic moment of the muon is the most demanding ledger in laboratory physics: a single number, measured to about two parts in ten million, in which the vacuum appears not as one entry but as several, each computed by different means. This paper lays out the ledger in units of 10^-10: quantum electrodynamics contributes 116584.72, the electroweak interaction 15.36, hadronic vacuum polarisation 693.1 at leading order with -9.8 at higher order, and hadronic light-by-light scattering 9.2, summing to 117292.6. The hadronic polarisation entry, a fraction 5.909e-03 of the total, is the vacuum's hadronic face, the same quark-loop physics that sets vacuum structure at the QCD scale, and it limits the comparison between theory and experiment. The ledger demonstrates that vacuum polarisation is not a hypothesis in this subject but a set of audited entries, each larger than the experimental error bar. The values are stated published-size entries, summed and compared in the script; no new measurement is reported.