Hyperfine splitting in ordinary and muonic hydrogen

Abstract

We provide an accurate evaluation of the two-photon exchange correction to the hyperfine splitting of S energy levels in muonic hydrogen exploiting the corresponding measurements in electronic hydrogen. The proton structure uncertainty in the calculation of ${\alpha }^5$ contribution is sizably reduced.

Comments: 5 pages, 4 figures, update in radiative corrections, the resulting HFS is provided, version published in Eur. Phys. J. A 54: 3 (2018)