# Quantum electrodynamic corrections to the $1s3d$ states of the helium atom

## TL;DR

This paper presents detailed quantum electrodynamic calculations of the ionization energies of helium's 1s3d states, revealing significant nonradiative corrections that impact theoretical predictions and highlight ongoing discrepancies with experimental data.

## Contribution

It provides the first complete evaluation of the mα^6 correction for these states, identifying a large nonradiative contribution previously unaccounted for.

## Key findings

- Nonradiative mα^6 correction significantly shifts ionization energy predictions.
- Theoretical predictions are affected by about 10 sigma due to this correction.
- Systematic deviations between theory and experiment for 3D states persist, reason unknown.

## Abstract

We perform quantum electrodynamic calculations of the ionization energy of the $1s3d$ states of the $^4$He atom, including a complete evaluation of the $m\alpha^6$ 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 10$\,\sigma$. 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.