The fundamental constants and their variation: observational and theoretical status
Abstract
This article describes the various experimental bounds on the variation of the fundamental constants of nature. After a discussion of the role of fundamental constants, their definition and link with metrology, it reviews the various constraints on the variation of the finestructure constant, the gravitational, weak and stronginteraction couplings and the electrontoproton mass ratio. The review aims (1) to provide the basics of each measurement, (2) to show as clearly as possible why it constrains a given constant, and (3) to point out the underlying hypotheses. Such an investigation is of importance in comparing the different results and in understanding the recent claims of the detection of a variation of the finestructure constant and of the electrontoproton mass ratio in quasar absorption spectra. The theoretical models leading to the prediction of such variation are also reviewed, including KaluzaKlein theories, string theories, and other alternative theories. Cosmological implications of these results are also discussed. The links with the tests of general relativity are emphasized.
 Publication:

Reviews of Modern Physics
 Pub Date:
 April 2003
 DOI:
 10.1103/RevModPhys.75.403
 arXiv:
 arXiv:hepph/0205340
 Bibcode:
 2003RvMP...75..403U
 Keywords:

 04.20.Cv;
 06.20.Jr;
 04.20.Gz;
 04.50.+h;
 11.25.w;
 Fundamental problems and general formalism;
 Determination of fundamental constants;
 Spacetime topology causal structure spinor structure;
 Gravity in more than four dimensions KaluzaKlein theory unified field theories;
 alternative theories of gravity;
 Strings and branes;
 High Energy Physics  Phenomenology;
 Astrophysics;
 General Relativity and Quantum Cosmology;
 High Energy Physics  Theory
 EPrint:
 56 pages, l7 figures, submitted to Rev. Mod. Phys