New Limits to the Drift of Fundamental Constants from Laboratory Measurements

Abstract

We have remeasured the absolute $1S$-$2S$ transition frequency $\hat{I}{½}_{\mathrm{H}}$ in atomic hydrogen. A comparison with the result of the previous measurement performed in 1999 sets a limit of $(-29\pm 57)$ Hz for the drift of $\hat{I}{½}_{\mathrm{H}}$ with respect to the ground state hyperfine splitting $\hat{I}{½}_{\mathrm{Cs}}$ in ${}^{133}$Cs. Combining this result with the recently published optical transition frequency in ${}^{199}$Hg${}^{+}$ against $\hat{I}{½}_{\mathrm{Cs}}$ and a microwave ${}^{87}$Rb and ${}^{133}$Cs clock comparison, we deduce separate limits on $\dot{\hat{I}}\pm /\hat{I}\pm =(-0.9\pm 2.9)\times 10^{-15}$ yr${}^{-1}$ and the fractional time variation of the ratio of Rb and Cs nuclear magnetic moments $\hat{I}{¼}_{\mathrm{Rb}}/\hat{I}{¼}_{\mathrm{Cs}}$ equal to $(-0.5\pm 1.7)\times 10^{-15}$ yr${}^{-1}$. The latter provides information on the temporal behavior of the constant of strong interaction.

4 pages, 3 figures, LaTeX