Extraction of the strong neutron-proton mass difference from the charge symmetry breaking in pn-->d pi0
arXiv:0907.4671 · doi:10.1016/j.physletb.2009.10.069
Abstract
We perform a complete calculation of charge symmetry breaking effects for the reaction pn -> d pi0 at leading order in chiral perturbation theory. A new leading-order operator is included. From our analysis we extract δm_N^{str}, the strong contribution to the neutron-proton mass difference. The value obtained, δm_N^{str} = 1.5 \pm 0.8 (exp.) \pm 0.5 (th.) MeV, is consistent with the result based on the Cottingham sum rule. This agreement provides a non-trivial test of our current understanding of the chiral structure of QCD.
11 pages, 2 figures, revised version accepted by PLB