High-precision measurement of the atomic mass of the electron

• Published in: Nature (London) Vol. 506; no. 7489; pp. 467 - 470
• Main Authors: Sturm, S., Köhler, F., Zatorski, J., Wagner, A., Harman, Z., Werth, G., Quint, W., Keitel, C. H., Blaum, K.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 27.02.2014; Nature Publishing Group
• Subjects: 140/58; 639/766/36/1122; 639/766/419/1131; 639/766/419/1133; Analysis; Atomic mass; Carbon; Electrons; Humanities and Social Sciences; letter; Magnetic fields; Magnetism; Measurement; multidisciplinary; Physics; Science; Structure
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/nature13026

A very precise measurement of the magnetic moment of a single electron bound to a carbon nucleus, combined with a state-of-the-art calculation in the framework of bound-state quantum electrodynamics, gives a new value of the atomic mass of the electron that is more precise than the currently accepted one by a factor of 13. Electron mass to unprecedented precision The atomic mass of the electron is a key parameter for fundamental physics. A precise determination is a challenge because the mass is so low. Sven Sturm and colleagues report on a new determination of the electron's mass in atomic units. The authors measured the magnetic moment of a single electron bound to a reference ion (a bare nucleus of carbon-12). The results were analysed using state-of-the-art quantum electrodynamics theory to yield a mass value with a precision that exceeds the current literature value by more than an order of magnitude. The quest for the value of the electron’s atomic mass has been the subject of continuing efforts over the past few decades 1 , 2 , 3 , 4 . Among the seemingly fundamental constants that parameterize the Standard Model of physics 5 and which are thus responsible for its predictive power, the electron mass m e is prominent, being responsible for the structure and properties of atoms and molecules. It is closely linked to other fundamental constants, such as the Rydberg constant R ∞ and the fine-structure constant α (ref. 6 ). However, the low mass of the electron considerably complicates its precise determination. Here we combine a very precise measurement of the magnetic moment of a single electron bound to a carbon nucleus with a state-of-the-art calculation in the framework of bound-state quantum electrodynamics. The precision of the resulting value for the atomic mass of the electron surpasses the current literature value of the Committee on Data for Science and Technology (CODATA 6 ) by a factor of 13. This result lays the foundation for future fundamental physics experiments 7 , 8 and precision tests of the Standard Model 9 , 10 , 11 .