The helium fine-structure controversy

TL;DR

This paper investigates the disagreement between theoretical and experimental values of helium's fine-structure splitting, identifying a potential minor error in previous calculations that could partially explain the discrepancy.

Contribution

It identifies a possible minor error in prior theoretical calculations of helium's fine-structure splitting, offering an explanation for the existing disagreement.

Findings

Potential minor error found in previous formulas

Possible partial resolution of the discrepancy

Further investigation needed to confirm impact

Abstract

There is presently disagreement between theory and experiment as well as between different theoretical calculations concerning the fine-structure splitting of the lowest P state of the neutral helium atom. We believe that we have found a minor error in the formulas used by Drake et al. (Can. J. Phys. 80, 1195 (2002)) in their calculations, and we may have an explanation how the error has occurred. To what extent this might resolve (part of) the discrepancy is not known at present.