Cottingham formula and nucleon polarizabilities
Abstract
The difference between the electromagnetic self-energies of proton and neutron can be calculated with the Cottingham formula, which expresses the self-energies as an integral over the electroproduction cross sections---provided the nucleon matrix elements of the current commutator do not contain a fixed pole. We show that, under the same proviso, the subtraction function occurring in the dispersive representation of the virtual Compton forward scattering amplitude is determined by the cross sections. The representation in particular leads to a parameter-free sum rule for the nucleon polarizabilities. We evaluate the sum rule for the difference between the electric polarizabilities of proton and neutron by means of the available parameterizations of the data and compare the result with experiment.
Keywords
Cite
@article{arxiv.1506.06747,
title = {Cottingham formula and nucleon polarizabilities},
author = {J. Gasser and M. Hoferichter and H. Leutwyler and A. Rusetsky},
journal= {arXiv preprint arXiv:1506.06747},
year = {2020}
}
Comments
30 pages, 7 figures; The typos in Eqs. (10), (27), (56), (57), (63) and (B.46) are corrected. None of the results of the paper is affected