108 research outputs found
Study of hyperfine structure in simple atoms and precision tests of the bound state QED
We consider the most accurate tests of bound state QED, precision theory of
simple atoms, related to the hyperfine splitting in light hydrogen-like atoms.
We discuss the HFS interval of the 1s state in muonium and positronium and of
the 2s state in hydrogen, deuterium and helium-3 ion. We summarize their QED
theory and pay attention to involved effects of strong interactions. We also
consider recent optical measurements of the 2s HFS interval in hydrogen and
deuterium.Comment: presented at The International Workshop "e+e- collisions from phi to
psi
Nonresonant effects in one- and two-photon transitions
We investigate nonresonant contributions to resonant Rayleigh scattering
cross sections of atoms. The problematic nonresonant contributions set a limit
to the accuracy to which atomic spectra determine energy levels. We discuss the
off-resonance effects in one-photon transitions. We also show that
off-resonance contributions for the 1S-2S two-photon transition in atomic
hydrogen are negligible at current and projected levels of experimental
accuracy. The possibility of a differential measurement for the detection of
off-resonance effects in one-photon transitions in atomic hydrogen is
discussed.Comment: 13 pages, LaTeX, 3 figures; submitted to Can. J. Phys. (Oct 2001);
discussion of one-photon transitions enhance
Toward high-precision values of the self energy of non-S states in hydrogen and hydrogen-like ions
The method and status of a study to provide numerical, high-precision values
of the self-energy level shift in hydrogen and hydrogen-like ions is described.
Graphs of the self energy in hydrogen-like ions with nuclear charge number
between 20 and 110 are given for a large number of states. The self-energy is
the largest contribution of Quantum Electrodynamics (QED) to the energy levels
of these atomic systems. These results greatly expand the number of levels for
which the self energy is known with a controlled and high precision.
Applications include the adjustment of the Rydberg constant and atomic
calculations that take into account QED effects.Comment: Minor changes since previous versio
Minimal Length Uncertainty Relation and the Hydrogen Spectrum
Modifications of Heisenberg's uncertainty relations have been proposed in the
literature which imply a minimum position uncertainty. We study the low energy
effects of the new physics responsible for this by examining the consequent
change in the quantum mechanical commutation relations involving position and
momenta. In particular, the modifications to the spectrum of the hydrogen atom
can be naturally interpreted as a varying (with energy) fine structure
constant. From the data on the energy levels we attempt to constrain the scale
of the new physics and find that it must be close to or larger than the weak
scale. Experiments in the near future are expected to change this bound by at
least an additional order of magnitude.Comment: 8 pages, no figure. Corrected typos, added a reference with comment
A constraint on antigravity of antimatter from precision spectroscopy of simple atoms
Consideration of antigravity for antiparticles is an attractive target for
various experimental projects. There are a number of theoretical arguments
against it but it is not quite clear what kind of experimental data and
theoretical suggestions are involved. In this paper we present straightforward
arguments against a possibility of antigravity based on a few simple
theoretical suggestions and some experimental data. The data are: astrophysical
data on rotation of the Solar System in respect to the center of our galaxy and
precision spectroscopy data on hydrogen and positronium. The theoretical
suggestions for the case of absence of the gravitational field are: equality of
electron and positron mass and equality of proton and positron charge. We also
assume that QED is correct at the level of accuracy where it is clearly
confirmed experimentally
One- and two-photon resonant spectroscopy of hydrogen and anti-hydrogen atoms in external electric fields
The resonant spectra of hydrogen and anti-hydrogen atoms in the presence of
an external electric field are compared theoretically. It is shown that
nonresonant corrections to the transition frequency contain terms linear in the
electric field. The existence of these terms does not violate space and time
parity and leads to a difference in the resonant spectroscopic measurements for
hydrogen and anti-hydrogen atoms in an external electric field. The one-photon
1s-2p and the two-photon 1s-2s resonances are investigated
Theory of muonic hydrogen - muonic deuterium isotope shift
We calculate the corrections of orders alpha^3, alpha^4 and alpha^5 to the
Lamb shift of the 1S and 2S energy levels of muonic hydrogen (mu p) and muonic
deuterium (mu d). The nuclear structure effects are taken into account in terms
of the proton r_p and deuteron r_d charge radii for the one-photon interaction
and by means of the proton and deuteron electromagnetic form factors in the
case of one-loop amplitudes. The obtained numerical value of the isotope shift
(mu d) - (mu p) for the splitting (1S-2S) 101003.3495 meV can be considered as
a reliable estimation for corresponding experiment with the accuracy 10^{-6}.
The fine structure interval E(1S)-8E(2S) in muonic hydrogen and muonic
deuterium are calculated.Comment: 22 pages, 7 figure
The First Cold Antihydrogen
Antihydrogen, the atomic bound state of an antiproton and a positron, was
produced at low energy for the first time by the ATHENA experiment, marking an
important first step for precision studies of atomic antimatter. This paper
describes the first production and some subsequent developments.Comment: Invitated Talk at COOL03, International Workshop on Beam Cooling and
Related Topics, to be published in NIM
Ultra-precise measurement of optical frequency ratios
We developed a novel technique for frequency measurement and synthesis, based
on the operation of a femtosecond comb generator as transfer oscillator. The
technique can be used to measure frequency ratios of any optical signals
throughout the visible and near-infrared part of the spectrum. Relative
uncertainties of for averaging times of 100 s are possible. Using a
Nd:YAG laser in combination with a nonlinear crystal we measured the frequency
ratio of the second harmonic at 532 nm to the fundamental at
1064 nm, .Comment: 4 pages, 4 figure
Asymmetry of the natural line profile for the hydrogen atom
The asymmetry of the natural line profile for transitions in hydrogen-like
atoms is evaluated within a QED framework. For the Lyman-alpha
absorption transition in neutral hydrogen this asymmetry results in an
additional energy shift of 2.929856 Hz. For the transition
it amounts to -1.512674 Hz. As a new feature this correction turns out to be
process dependent. The quoted numbers refer to the Compton-scattering process.Comment: RevTex, 7 Latex pages, 1 figur
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