The anomalous magnetic moment of the electron

• Published in: Contemporary physics Vol. 50; no. 3; pp. 437 - 452
• Main Author: Vogel, M.
• Format: Journal Article
• Language: English
• Published: Colchester Taylor & Francis 01.05.2009; Taylor & Francis Ltd
• Subjects: bound-state QED; Determination of fundamental constants; electron magnetic moment; Electrons; Electrons (including positrons); Exact sciences and technology; fundamental constants; g-factor; Leptons; Magnetic fields; magnetic moment anomaly; Metrology; Metrology, measurements and laboratory procedures; Physics; Properties of specific particles; Quantum electrodynamics; Quantum physics; Specific theories and interaction models; particle systematics; Stern-Gerlach effect; The physics of elementary particles and fields; Fine structure; Fine structure constant; Quantum electrodynamics; Magnetic moments; Measuring methods; Quantum field theory; Quantum theory
• ISSN: 0010-7514; 1366-5812
• DOI: 10.1080/00107510902765239

The value of the electron's magnetic moment is a fundamental quantity in physics. Its deviation from the value expected from Dirac theory has given enormous impetus to the field of quantum theory and especially to quantum electrodynamics (QED) as the relativistic quantum field theory of electrodynamics. In fact, the measured values both for free and for bound electrons are explained by corresponding QED calculations on the part per trillion and part per billion level of accuracy, respectively. This agreement is amongst the best known in physics today. In turn, it allows highly precise determinations of related fundamental constants like the fine structure constant α or the electron mass. The present article discusses the application of the continuous Stern-Gerlach effect to the precise measurement of magnetic moments, especially of the electron bound in highly charged ions and possible tests of calculations in the framework of QED of bound states. Also, a test of QED in a more general approach by the comparison of values for the fine structure constant derived from different measurements, will be discussed.