Negative-continuum effects on the two-photon decay rates of hydrogenlike ions

Citation:
Surzhykov, A., J. P. Santos, P. Amaro, and P. Indelicato. "Negative-continuum effects on the two-photon decay rates of hydrogenlike ions." Physical Review A (Atomic, Molecular, and Optical Physics) 80 (2009): 052511.

Abstract:

Two-photon decay of hydrogenlike ions is studied within the framework of second-order perturbation theory, based on the relativistic Dirac's equation. Special attention is paid to the effects arising from the summation over the negative-energy (intermediate virtual) states that occur in such a framework. In order to investigate the role of these states, detailed calculations have been carried out for the 2s1/2–>1s1/2 and 2p1/2–>1s1/2 transitions in neutral hydrogen H as well as for hydrogenlike xenon Xe53+ and uranium U91+ ions. We found that for a correct evaluation of the total and energy-differential decay rates, summation over the negative-energy part of Dirac's spectrum should be properly taken into account both for high-Z and low-Z atomic systems.

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