Light antiproton one-electron quasi-molecular ions within the relativistic A-DKB method.

In the present work, two quasi-molecular compounds each involving one antiproton and one electron (p̄), He+-p̄ and H-p̄, are investigated. Using completely relativistic calculations within the finite-basis method adapted to systems with axial symmetry, the adiabatic potential curves are constructed by numerically solving the two-center Dirac equation. The binding energies of electron are obtained as a function of the inter-nuclear distance and compared with the corresponding nonrelativistic values and relativistic leading-order corrections calculated in the framework of other approaches.

Theoretical study of the accuracy limits of optical resonance frequency measurements.

The principal limits for the accuracy of the resonance frequency measurements set by the asymmetry of the natural resonance line shape are studied and applied to the recent accurate frequency measurements in the two-photon 1s-2s resonance and in the one-photon 1s-2p resonance in a hydrogen atom. This limit for 1s-2s resonance is found to be approximately 10(-5) Hz compared to the accuracy achieved in experiment +/-46 Hz. In the case of a deuterium atom the limit is essentially larger: 10(-2) Hz.

Asymmetry of the natural line profile for the hydrogen atom.

The asymmetry of the natural line profile for transitions in hydrogenlike atoms is evaluated within a QED framework. For the Lyman- alpha 1s-2p absorption transition in neutral hydrogen this asymmetry results in an additional energy shift of 2.929 856 Hz.