Eur. Phys. J. D 61, 7-14 (2011)
https://doi.org/10.1140/epjd/e2010-10414-6

Proton radius, Darwin-Foldy term and radiative corrections

Department of Physics, Missouri University of Science and Technology, MO 65409-0640 Rolla, USA Institut für Theoretische Physik, Universität Heidelberg, Philosophenweg 16, 69120 Heidelberg, Germany

Corresponding author: ^a ulj@mst.edu

Received: 20 July 2010
Revised: 23 September 2010
Published online: 10 November 2010

Abstract

We discuss the role of the so-called Darwin-Foldy term in the evaluation of the proton and deuteron charge radii from atomic hydrogen spectroscopy and nuclear scattering data. The question of whether this term should be included or excluded from the nuclear radius has been controversially discussed in the literature. We attempt to clarify which literature values correspond to which conventions. A detailed discussion of the conventions appears useful because a recent experiment [R. Pohl et al., Nature 466, 213 (2010)] has indicated that there is a discrepancy between the proton charge radii inferred from ordinary (“electronic”) atomic hydrogen and muonic hydrogen. We also investigate the role of quantum electrodynamic radiative corrections in the determination of nuclear radii from scattering data, and propose a definition of the nuclear self energy which is compatible with the subtraction of the radiative corrections in scattering experiments.