Two-loop QED corrections with closed fermion loops for the bound-electron g factor

TL;DR

This paper calculates two-loop QED corrections with closed fermion loops to the 1s bound-electron g factor, providing precise results across all nuclear charge strengths and comparing with previous expansion methods.

Contribution

It introduces a comprehensive calculation of two-loop QED corrections for the bound-electron g factor, including higher-order remainders, extending beyond previous Zα-expansion approaches.

Findings

Calculated corrections for all Zα values

Separated higher-order remainders of order α^2(Zα)^5 and above

Compared results with previous expansion calculations

Abstract

Two-loop QED corrections with closed fermion loops are calculated for the 1s bound-electron g factor. Calculations are performed to all orders in the nuclear binding strength parameter Z\alpha (where Z is the nuclear charge and \alpha is the fine structure constant) except for the closed fermion loop, which is treated within the free-loop (Uehling) approximation in some cases. Comparison with previous Z\alpha-expansion calculations is made and the higher-order remainder of order \alpha^2(Z\alpha)^5 and higher is separated out from the numerical results.