Charge symmetry breaking in pion production
Abstract
Chiral effective field theory predicts a charge symmetry violating (CSB) amplitude for pion-nucleon scattering. This mechanism provides a very large contribution also to the CSB forward-backward asymmetry in the angular distribution of the reaction pn --> d pi0. This contribution was so large that it had a potential to cause a large effect also in CSB elastic NN scattering and to disturb its present understanding. However, it can be seen that, contrary to pion production, in this case the ud-quark mass difference and the electromagnetic contribution to the np-mass difference tend to cancel causing the total effect in the effective range parameters Delta a = a_pp - a_nn and Delta r_0 = r_0,pp - r_0,nn to be relatively small. In the lowest order and within the static approximation for the nucleons CSB pion-nucleon rescattering does not influence np scattering.
Keywords
Cite
@article{arxiv.nucl-th/0207046,
title = {Charge symmetry breaking in pion production},
author = {J. A. Niskanen},
journal= {arXiv preprint arXiv:nucl-th/0207046},
year = {2017}
}
Comments
5 pages including 1 eps figure; Talk at the 7th Int. Workshop on Meson Production, Properties and Interactions, MESON2002, May 2002, Cracow