Improved theoretical prediction for the 2s hyperfine interval in helium ion
Abstract
We consider the uncertainty of theoretical calculations for a specific difference of the hyperfine intervals in the 1s and 2s states in a light hydrogen-like atom. For a number of crucial radiative corrections the result for hydrogen atom and helium ion appears as an extrapolation of the numerical data from medium to low Z. An approach to a plausible estimation of the uncertainty is suggested using the example of the difference
D
21
=8
E
hfs
(2s)−
E
hfs
(1s)
.