Fine structure of helium-like ions and determination of the fine structure constant

TL;DR

This paper presents precise calculations of fine structure splitting in helium-like ions, resolving previous discrepancies and enabling an accurate determination of the fine structure constant with 31 parts per billion precision.

Contribution

The study provides comprehensive quantum electrodynamical calculations up to order α^5 Ry, improving theoretical-experimental agreement and refining the value of the fine structure constant.

Findings

Resolved the theory-experiment discrepancy for helium fine structure

Achieved 31 ppb accuracy in determining the fine structure constant

Validated calculations across different nuclear charges

Abstract

We report a calculation of the fine structure splitting in light helium-like atoms, which accounts for all quantum electrodynamical effects up to order \alpha^5 Ry. For the helium atom, we resolve the previously reported disagreement between theory and experiment and determine the fine structure constant with an accuracy of 31 ppb. The calculational results are extensively checked by comparison with the experimental data for different nuclear charges and by evaluation of the hydrogenic limit of individual corrections.