Dominant 2πγ-exchange nucleon-nucleon interaction: Spin-spin and tensor potentials

We calculate at two-loop order in chiral perturbation theory the electromagnetic corrections to the two-pion exchange nucleon-nucleon interaction that is generated by the isovector spin-flip ππNN contact-vertex proportional to the large low-energy constant c4 3.4GeV-1. We find that the respective 2πγ-exchange potentials contain sizable isospin-breaking components which reach up to -4% of corresponding isovector 2π-exchange potentials. The typical values of these novel charge-independence breaking spin-spin and tensor potentials are -0.11 and 0.09 MeV, at a nucleon distance of r=mπ-1=1.4 fm. The charge-symmetry breaking spin-spin and tensor potentials come out a factor of 2.4 smaller. Our analytical results for these presumably dominant isospin-violating spin-spin and tensor NN-forces are in a form such that they can be easily implemented into phase-shift analyses and few-body calculations.