$\Delta(1232)$-Resonance in the Hydrogen Spectrum
Abstract
The electromagnetic excitation of the -resonance plays an appreciable role in the Lamb shift and hyperfine structure of muonic and electronic hydrogen. Its effect appears at the subleading order , together with other proton-polarizability contributions from forward two-photon exchange. We use the large- relations for the nucleon-to-delta transition form factors to compute the effect of the in the hydrogen spectrum. We pay particular attention to a subtile difference between predictions based on a direct calculation of the two-photon exchange (or Compton scattering amplitudes) and predictions based on the -production photoabsorption cross sections. The mismatch is explained by studying the dispersion relations for tree-level Compton scattering off the proton in more details.
Keywords
Cite
@article{arxiv.1801.09790,
title = {$\Delta(1232)$-Resonance in the Hydrogen Spectrum},
author = {Franziska Hagelstein},
journal= {arXiv preprint arXiv:1801.09790},
year = {2018}
}
Comments
Contribution to the Proceedings of the 11. International Workshop on the Physics of Excited Nucleons, 19 pages, 6 figures, 3 tables, references and comments added