ABSTRACT
Constraint on spin-dependent and spin-independent Yukawa potential at atomic scale is developed. That covers constraints on a coupling constant of an additional photon γ* and a pseudovector boson. The mass range considered is from 1 eV/c2 to 1 MeV/c2. The strongest constraint on a coupling constant α' is at the level of a few parts in 10913) (for γ*) and below one part in 10(16) (for a pseudovector) corresponding to mass below 1 keV/c2. The constraints are derived from low-energy tests of quantum electrodynamics and are based on spectroscopic data on light hydrogenlike atoms and experiments with magnetic moments of leptons and light nuclei.
ABSTRACT
An optical measurement of the 2S hyperfine interval in atomic hydrogen using two-photon spectroscopy of the 1S-2S transition gives a value of 177 556 834.3(6.7) Hz. The uncertainty is 2.4 times smaller than achieved by our group in 2003 and more than 4 times smaller than for any independent radio-frequency measurement. The specific combination of the 2S and 1S hyperfine intervals predicted by QED theory 8fHFS(2S)-fHFS(1S)=48 953(3) Hz is in good agreement with the value of 48 923(54) Hz obtained from this experiment.
ABSTRACT
The comparison of different atomic transition frequencies over time can be used to determine the present value of the temporal derivative of the fine structure constant alpha in a model-independent way without assumptions on constancy or variability of other parameters, allowing tests of the consequences of unification theories. We have measured an optical transition frequency at 688 THz in 171Yb+ with a cesium atomic clock at 2 times separated by 2.8 yr and find a value for the fractional variation of the frequency ratio f(Yb)/f(Cs) of (-1.2+/-4.4)x10(-15) yr(-1), consistent with zero. Combined with recently published values for the constancy of other transition frequencies this measurement sets an upper limit on the present variability of alpha at the level of 2.0x10(-15) yr(-1) (1sigma), corresponding so far to the most stringent limit from laboratory experiments.
ABSTRACT
We have applied an optical method to the measurement of the 2S hyperfine interval in atomic hydrogen. The interval has been measured by means of two-photon spectroscopy of the 1S-2S transition on a hydrogen atomic beam shielded from external magnetic fields. The measured value of the 2S hyperfine interval is equal to 177 556 860(16) Hz and represents the most precise measurement of this interval to date. The theoretical evaluation of the specific combination of 1S and 2S hyperfine intervals D21 is in fair agreement (within 1.4 sigma) with the value for D21 deduced from our measurement.
