Speaker
Description
Quantum Electrodynamics (QED) effects have been tested and measured in multiple systems, including free electrons, atomic and highly charged ions systems. Frequentist statistical analyses either point to a possible deviation from the theory prediction [1] of n = 2 → 1 transitions energy in two-electron systems with a dependency of Z^3, Z indicating the nuclear charge, or find no disagreement [2-5]. We present a Bayesian statistical approach method using the nested sampling algorithm, implemented in the nested fit code package [6], to quantitatively evaluate different deviations via probability inference from Bayesian evidence. The deviations are modeled as aZ^n and aZ^n+b functions, a and b being free parameters, for the measurements of multiple transitions on helium-like ions for Z = 12 − 92. We evaluated these modeled deviations from the current theory predictions [7, 8] for the 1s2p 1P1 → 1s2 1S0 (w), 1s2p 3P2 → 1s2 1S0 (x), 1s2p 3P1 → 1s2 1S0 (y), and 1s2p 3S1 → 1s2 1S0 (z) radiative transitions. We found that the function with highest probability corresponds to a deviation with n ≈ 4.5, but has a marginal statistical significance of 2.7σ with respect to the zero model with no deviation from the theory. The additional analysis of the n = 2 → 2 (Z = 5 − 92) transitions provided an even lesser evidence for either a constant or power model deviations. Finally, we investigated on the impact of possible future high-accuracy experiments on high-Z ions. In particular, we determine the minimum required accuracy for a meaningful test of possible deviations. We construct hypothetical measurement data in the Z region of interest, vary its uncertainty and value, and survey the behaviour of the probability distribution over the selected models for each combination. Such an analysis will allow for a better design of future experiments for the search of new QED contributions or even new physics, like milli-charged particle interactions.
References:
[1] C.T. Chantler et al., Phys. Rev. Lett. 109, 153001 (2012).
[2] S.W. Epp, Phys. Rev. Lett. 110, 159301 (2013).
[3] P. Beiersdorfer and G.V. Brown, Phys. Rev. A 91, 032514 (2015).
[4] J. Machado et al., Phys. Rev. A 97, 032517 (2018).
[5] P. Indelicato, J. Phys. B 52, 232001 (2019).
[6] M. Trassinelli, Proceedings 33, 14 (2019).
[7] A. N. Artemyev et al., Phys. Rev. A 71, 062104 (2005).
[8] V. A. Yerokhin et al., Phys. Rev. A 106, 022815 (2022).
