Finite nuclear mass correction to the hyperfine splitting in hydrogenic systems

A general quantum electrodynamic method for the derivation of nuclear recoil corrections in hydrogenic systems, which are exact in the nuclear charge parameter Z0.16em0exα, is introduced. The exemplary derivation is presented for the $O(m/M)$ nuclear pure recoil correction to the hyperfine splitting. The obtained result is verified by comparison to the known (Z0.16em0exα)⁵ contribution.