Quantum-electrodynamic corrections to the 1s3d states of the helium atom

We perform quantum-electrodynamic calculations of the ionization energy of the 1s3d states of the He4 atom, including a complete evaluation of the mα6 correction. We find a large contribution from the nonradiative part of this correction, which has not been accounted for in previous investigations. The additional contribution shifts theoretical predictions for ionization energies by about 10σ. Despite this shift, we confirm the previously reported systematic deviations between measured experimental results and theoretical predictions for transitions involving 3D states. The reason for these deviations remains unknown.</p>