ConstantID

Electron magnetic moment anomaly

Atomic & nuclearMeasured

ae = 1.159 652 180 46(18) × 10−3

Value
1.159 652 180 46 × 10−3
Standard uncertainty
1.8 × 10−13
Relative uncertainty
1.6 × 10−10 (155 parts per trillion)
Status
Measured
Symbol
ae
Source
CODATA 2022 via NIST · NIST entry

Use in a calculation

# electron magnetic moment anomaly, CODATA 2022 (NIST)
electron_magnetic_moment_anomaly = 1.15965218046e-3  # standard uncertainty 1.8e-13

# SciPy: scipy.constants.physical_constants['electron mag. mom. anomaly']

What it is

How far the electron's g-factor differs from Dirac's value of 2, divided by 2. Comparing its measured value with the quantum electrodynamics prediction is one of the main ways the fine-structure constant is determined.

Equations

  • ae=|ge|−22≈α2πSchwinger's leading term

How the value changed, 1998–2022

Each point is one CODATA adjustment, plotted as its difference from the 2022 value; the bars show one standard uncertainty (an arrowhead means the bar runs off the chart).

electron magnetic moment anomaly: CODATA values 1998–2022 relative to the 2022 value, in parts per billion, with one-standard-uncertainty bars−10−50+5+10parts per billion1998200220062010201420182022

Relative uncertainty

electron magnetic moment anomaly: relative standard uncertainty in each CODATA adjustment, logarithmic scale10⁻¹⁰10⁻⁹10⁻⁸1998200220062010201420182022
CODATAValue (uncertainty)Relative uncertaintyChange from previous
20221.159 652 180 46(18) × 10−31.6 × 10−10 −4.6 σ of 2018
20181.159 652 181 28(18) × 10−31.6 × 10−10 +1.4 σ of 2014
20141.159 652 180 91(26) × 10−32.2 × 10−10 +0.6 σ of 2010
20101.159 652 180 76(27) × 10−32.3 × 10−10 −0.5 σ of 2006
20061.159 652 181 11(74) × 10−36.4 × 10−10 −1.3 σ of 2002
20021.159 652 1859(38) × 10−33.3 × 10−9 −0.2 σ of 1998
19981.159 652 1869(41) × 10−33.5 × 10−9

“Change from previous” is the shift in the value divided by the standard uncertainty of the previous adjustment. Earlier values are converted into the current unit where NIST changed it (for example J s to J Hz⁻¹).

Related constants

Atomic & nuclear ge Electron g-factor −2.002 319 304 360 92(36) Atomic & nuclear α Fine-structure constant 7.297 352 5643(11) × 10−3 Atomic & nuclear aμ Muon g−2 1.165 920 62(41) × 10−3 Atomic & nuclear −e/me Electron charge to mass quotient −1.758 820 008 38(55) × 1011 C kg−1 Atomic & nuclear μe/μd Electron-deuteron magnetic moment ratio −2143.923 4921(56) Atomic & nuclear me/md Electron-deuteron mass ratio 2.724 437 107 629(47) × 10−4 Atomic & nuclear γe Electron gyromagnetic ratio 1.760 859 627 84(55) × 1011 s−1 T−1 Atomic & nuclear γe/2π Electron gyromagnetic ratio in MHz/T 28 024.951 3861(87) MHz T−1