Isospin breaking in pion-nucleon scattering at threshold by radiative processes
High Energy Physics - Phenomenology
2007-05-23 v1
Abstract
We investigate the dispersive contribution by radiative processes such as (pi- proton to neutron gamma) and (pi- proton to Delta gamma) to the pion-nucleon scattering lengths of charged pions in the heavy baryon limit. They give a large isospin violating contribution in the corresponding isoscalar scattering length, but only a small violation in the isovector one. These terms contribute 6.3(3)% to the 1s level shift of pionic hydrogen and give a chiral constant F_pi^2f_1=-25.8(8) MeV.
Keywords
Cite
@article{arxiv.hep-ph/0503277,
title = {Isospin breaking in pion-nucleon scattering at threshold by radiative processes},
author = {T. E. O. Ericson and A. N. Ivanov},
journal= {arXiv preprint arXiv:hep-ph/0503277},
year = {2007}
}
Comments
9 pages with 1 figure