Imaging-Assisted Single-Photon Doppler-Free Laser Spectroscopy and the Ionization Energy of Metastable Triplet Helium

Towards Precision Muonic X-ray Measurements of Charge Radii of Light Nuclei

“…Considering the ongoing experiments aim to obtain an accuracy of the order of 100 kHz [66], an order-of-magnitude improvement in the radius would allow for the missing α 8 (α denotes the fine structure constant) theory contribution of the order 3 MHz, to be determined with an uncertainty of 10% [64]. Moreover, this effect can be downscaled to the analogous transition in the helium atom and to shed light on the observed, and recently confirmed, deviations between experiment and theory [67,68].…”

Bound-State Relativistic Quantum Electrodynamics: A Perspective for Precision Physics with Atoms and Molecules

“…The continuous development and ever-increasing precision of experimental methods facilitate increasingly stringent testing of theoretical calculations. 26−35 Ionization energies 35 and, more generally, atomic transition frequencies 26,33,34 of light elements (e.g., H, He) can be determined with uncertainties as low as 10 −12 to 10 −15 E h .…”

One-Particle Operator Representation over Two-Particle Basis Sets for Relativistic QED Computations

“…In particular, basis set methods as well as finite-element techniques were recently developed to compute high-precision eigenstates of the one-electron Dirac equation for H 2 + -like two-center systems to catch up with the increasing experimental accuracy. Precision spectroscopy and precision physics experiments are becoming available also for polyelectronic systems, ,, the ongoing (two-electron) triplet helium puzzle is an illustrative example. ,, …”

“…In particular, basis set methods 20 as well as finite-element techniques 21 were recently developed to compute high-precision eigenstates of the one-electron Dirac equation for H 2 + -like two-center systems to catch up with the increasing experimental accuracy. Precision spectroscopy and precision physics experiments are becoming available also for polyelectronic systems, 2,3,6 the ongoing (two-electron) triplet helium puzzle is an illustrative example. 3,6,18 Regarding the theoretical framework for two-electron and two-spin-1/2-fermion systems, we have recently elaborated 22−24 the Bethe−Salpeter equation 25 and its equal-time variant pioneered by Salpeter 26 and Sucher 27 (see also Araki 28 ).…”

“…Precision spectroscopy and precision physics experiments are becoming available also for polyelectronic systems, 2,3,6 the ongoing (two-electron) triplet helium puzzle is an illustrative example. 3,6,18 Regarding the theoretical framework for two-electron and two-spin-1/2-fermion systems, we have recently elaborated 22−24 the Bethe−Salpeter equation 25 and its equal-time variant pioneered by Salpeter 26 and Sucher 27 (see also Araki 28 ). The no-pair approximation to the equal-time Bethe−Salpeter(−Sucher) equation results in the no-pair Dirac−Coulomb(−Breit), in short, the DC(B) Hamiltonian.…”