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$α^4$ Ry corrections to singlet states of helium

Krzysztof Pachucki
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Abstract

Corrections of order $α^4$Ry are calculated for the singlet states $1^1S_0$ and $2^1S_0$ of the helium atom. The result for $1^1S_0$ state is in slight disagreement with that of Korobov and Yelkhovsky in [Phys. Rev. Lett. {\bf 87}, 193003 (2001)]. The results obtained lead to a significant improvement of transition frequencies between low lying levels of the helium atom. In particular theoretical predictions for the $2^1S_0 - 1^1S_0$ transition are found to be in disagreement with experimental values.

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Krzysztof Pachucki. 2006-07-07. $α^4$ Ry corrections to singlet states of helium. https://doi.org/10.1103/physreva.74.022512

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