The Hyperfine Puzzle of Strong-Field Bound-State QED
by Prof. Wilfried Nörtershäuser (Technische Universität Darmstadt)
at SMI - Boltzmanngasse 3, 1090 Wien ( 3-2-08 - Seminarraum )
Prof. Dr. Wilfried Nörtershäuser
The transition in lithium-like Bismuth was directly observed for the first time in 2011 at the experimental storage ring ESR located at GSI Darmstadt, but the accuracy of the result was limited by the imprecise knowledge of the ion velocity and the corresponding Doppler shift.
In a recent beamtime at the ESR, we were able to reduce the uncertainties in nearly all measured parameters and improved accuracy by more than an order of magnitude . To our surprise, the result was more than 7 sigma off the theoretical prediction and has established the "Hyperfine Puzzle of QED" .
I will report on the experiment, its outcome, possible solutions of the Puzzle and further strategies to test strong-field bound-state QED with higher accuracy.
 Nat. Commun., 8:15484 (2017)