Lea, S N
(2007)
*Limits to time variation of fundamental constants from comparisons of atomic frequency standards.*
Rep. Prog. Phys., 70 (9).
pp. 1473-1523.

## Abstract

Time variation of the fundamental constants is one manifestation of the violation of Einstein's Equivalence Principle required by theories uniting graviation with the strong and electroweak interactions. The rapid progress in the development of atomic frequency standards based on optical transitions is leading to ever more stringent constraints on time-variation of the fine structure constant, a , which is the coupling constant of the electromagnetic interaction, and to quantities such as nuclear g-factors and mass ratios, which depend on the strong interaction. Absolute frequency measurements of these optical frequency standards currently place a limit on present-day time variation of the fine structure constant of (-4 ± 4) parts in 10(to the power of 16) per year. There are good prospects for an improvement of two orders of magnitude in this limit by means of direct frequency comparisons between optical frequency standards.

Item Type: | Article |
---|---|

Subjects: | Time and Frequency Time and Frequency > Time |

Last Modified: | 02 Feb 2018 13:15 |

URI: | http://eprintspublications.npl.co.uk/id/eprint/3943 |

### Actions (login required)

View Item |