CODATA recommended values of the fundamental physical constants: 2002

Probing a Single Isolated Electron: New Measurements of the Electron Magnetic Moment and the Fine Structure Constant

“…The first result beyond g itself is the fine structure constant, α = e 2 /(4πǫ 0 c), determined from g and QED with ten times smaller uncertainty compared to any other method [8]. This fundamental measure of the strength of the electromagnetic interaction is a crucial ingredient in our system of fundamental constants [55]. Second, the most demanding test of QED continues to be a comparison of measured and calculated g-values, and the way is now prepared for a ten times more stringent test.…”

“…with an estimate x = 4.6 [55], while awaiting a daunting evaluation of contributions from 12672 Feynman diagrams that is now underway [62]. Also owing the high precision, non-QED contributions, …”

“…Electron substructure [52] would make g deviate from the Dirac/QED prediction (as quark-gluon substructure does for a proton). Measurements of the electron g have a long history [53,54], with a celebrated measurement [20] providing the accepted value [55] since 1987. The new g has a six times smaller standard deviation and is shifted by 1.7 standard deviations (Fig.…”

“…The fundamental fine structure constant, α = e 2 /(4πǫ 0 c), gives the strength of the elec-tromagnetic interaction, and is a crucial building block in our system of fundamental constants [55]. Quantum electrodynamics (QED), the wonderfully successful theory that describes the interaction of light and matter, provides an incredibly accurate prediction for the relationship between g and α, with only small corrections for short distance physics.…”

Antiproton–to–electron mass ratio determined by two-photon laser spectroscopy of antiprotonic helium atoms

“…3) agree with the theoretical frequencies ν th (squares) within a fractional precision of (2.3 − 5) × 10 −9 . The calculation uses the fundamental constants compiled in CODATA2002 [20], such as the 3 He-and 4 He-to-electron mass ratios, the Bohr radius, and Rydberg constant. The charge radii of the 3 He and 4 He nuclei give relatively small corrections to ν th of 4 − 7 MHz [5].…”