Pion-photon exchange nucleon-nucleon potentials

Abstract

We calculate in chiral perturbation theory the dominant next-to-leading order correction to the $\pi \gamma$-exchange NN-potential proportional to the large isovector magnetic moment ${\kappa }_v=4.7$ of the nucleon. The corresponding spin-spin and tensor potentials ${\tilde{V}}_{S,T}(r)$ in coordinate space have a very simple analytical form. At long distances $r\simeq 2$ fm these potentials are of similar size (but opposite in sign) as the leading order $\pi \gamma$-exchange potentials. We consider also effects from virtual $\Delta$-isobar excitation as well as other isospin-breaking contributions to the $2\pi$-exchange NN-potential induced by additional one-photon exchange.

Comments: 7 pages, 2 figures, to be published in Phys. Rev. C (2006) Brief Reports