2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/182042We calculate at two-loop order in chiral perturbation theory the electromagnetic corrections to the dominant two-pion exchange nucleon-nucleon interaction that is generated by the isoscalar $πN$ contact-vertex proportional to the large low-energy constant $c_3$. We find that the respective $2πγ$-exchange potential contains sizeable isospin-breaking components which amount to about -1% of the strongly attractive isoscalar central $2π$-exchange potential. The typical value of these novel charge-independence and charge-symmetry breaking central potentials is $0.3 $MeV at a nucleon distance of $r= m_π^{-1} = 1.4 $fm. Our analytical result for this presumably dominant $2πγ$-exchange interaction is in a form such that it can be easily implemented into phase-shift analyses and few-body calculations.7 pages, 1 figure, to be published in Physical Review C (2006): Brief ReportsNuclear Theorytext