2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/179532Phenomenological Lagrangians and dimensional power counting are used to assess isospin violation in the nucleon-nucleon force. The $πNN$ coupling constants (including the Goldberger-Treiman discrepancy), charge-symmetry breaking, and meson-mixing models are examined. A one-loop analysis of the isospin-violating $πNN$ coupling constants is performed using chiral perturbation theory. Meson-mixing models and the $^3$He - $^3$H mass difference are also discussed in the context of naturalness.10 pages, latex, 1 figure -- To appear in Physics Letters B -- epsfig.sty requiredNuclear TheoryHigh Energy Physics - Phenomenologytext