Anomalous magnetic moment
= Anomalous magnetic moment
{title2=$a=(g-2)/2$}
{wiki}
For a charged <spin one-half> particle with the <Dirac equation> reference value $g=2$, the <anomalous magnetic moment> is conventionally expressed by the dimensionless quantity $a=(g-2)/2$. For the <Electron>, write $a_e=(g_s-2)/2$. A stipulated $g_s=2.0024$ would therefore mean $a_e=0.0012$: a $0.12\%$ excess of the spin-component moment over one <Bohr magneton>. This is a teaching input, not a quoted measurement.