QED nuclear recoil effect in helium isotope shift
Phys. Rev. A 113, 012824 – Published 26 January, 2026
DOI: https://doi.org/10.1103/3p73-984r
Abstract
We present a detailed investigation of the leading-order QED correction with inclusion of the finite-nuclear-mass effects. Previously, this correction had been calculated within an expansion in the electron-nucleus mass ratio up to the first order. In this work, we derive formulas for the QED contribution that are valid up to the second order, and perform its calculation for the isotope shift, leading to an improved determination of the nuclear-charge-radius difference.