Karshenboim, S. G.Ozawa, A.Shelyuto, V. A.Korzinin, E. Yu...
14页
查看更多>>摘要：Precision studies of simple atoms, such as hydrogen, play an essential role in tests of bound-state QED and determining fundamental constants, such as the Rydberg constant and the proton charge radius. One of the QED predictions is for the Lamb shift of hydrogenic energy levels and, in particular, of the ground state. The value of the is Lamb shift in hydrogen and deuterium is required for an accurate determination of the Rydberg constant and the proton charge radius utilizing data from high-resolution spectroscopy of hydrogen and deuterium atoms, as well as for precision tests of bound-state QED. The dominant QED contribution to the uncertainty is due to the alpha(8)m external-field contributions. We discuss here our recent results on the two-and three-loop contributions, which essentially reduce the theoretical uncertainty. Combined with recent calculations of Laporta on the slope of the Dirac form factor in the three-loop level, our results allow for completion of calculations of alpha(8)m contributions to the Lamb shift of the ground state in the hydrogen atom.
Dubinov, A. E.Saikov, S. K.Selemir, V. D.Tarakanov, V. P....
37页
查看更多>>摘要：Results of PIC simulation of the phase dynamics of counter-propagating overlimiting electron beams injected in opposite directions into various axially symmetric cavities are reviewed. Multiple examples of the complex dynamics of the beams are presented, in which virtual cathodes, phase-space holes, and squeezed state regions containing a dense charged electron plasma are formed. Space and time characteristics of the processes and the density, temperature, and lifetime of the electron plasma are estimated. Possible experiments and potential applications of counter-propagating overlimiting electron beams in various areas of science and technology are considered, including RF electronics, ultra-wideband electronics, particle accelerators, and electric discharges in gases.
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