2000 character limit reached
Precision Test of Many-Body QED in the Be$^+$ $2p$ Fine Structure Doublet Using Short-Lived Isotopes (1507.03830v1)
Published 14 Jul 2015 in physics.atom-ph
Abstract: Absolute transition frequencies of the $2s\; 2{\rm S}{1/2} \rightarrow 2p\;2\mathrm{P}{1/2,3/2}$ transitions in Be$+$ were measured for the isotopes ${7,9-12}$Be. The fine structure splitting of the $2p$ state and its isotope dependence are extracted and compared to results of \textit{ab initio} calculations using explicitly correlated basis functions, including relativistic and quantum electrodynamics effects at the order of $m \alpha6$ and $m \alpha7 \ln \alpha$. Accuracy has been improved in both the theory and experiment by 2 orders of magnitude, and good agreement is observed. This represents one of the most accurate tests of quantum electrodynamics for many-electron systems, being insensitive to nuclear uncertainties.