We perform ab initio calculations of the QED effects of order $m{\alpha }^7$ for the $2{}^{3}S$ and $2{}^{3}P$ states of He-like ions. The computed effects are combined with previously calculated energies [V. A. Yerokhin and K. Pachucki, Phys. Rev. A 81, 022507 (2010)], thus improving the theoretical accuracy by an order of magnitude. The obtained theoretical values for the $2{}^{3}S-2{}^{3}P_{0,2}$ transition energies are in good agreement with available experimental results and with previous calculations performed to all orders in the nuclear binding strength parameter $Z\alpha$. For the ionization energies, however, we find some inconsistency between the $Z\alpha$-expansion and all-order calculations, which might be related to a similar discrepancy between the theoretical and experimental results for the ionization energies of helium [V. Patkóš et al., Phys. Rev. A 103, 042809 (2021)].

• Received 30 November 2022
• Accepted 6 January 2023

DOI:https://doi.org/10.1103/PhysRevA.107.012810