2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/184079The narrow charmonium state near 3872 MeV reported by the Belle collaboration and confirmedby CDF lies almost exactly at the neutral D anti-D* threshold. As was predicted many years ago it can be a deuteronlike meson-meson state called a deuson. If so, it should be an axial, or possibily a pseudoscalar state with C=0, and isospin predominantly 0. Large isospin breaking is expected because of the isospin mass splitting between the neutral and charged D (D*) mesons. Because of this large isospin breaking the decay X(3872) to J/psi rho would be allowed, while J/psi sigma would be forbidden by C-parity, as indicated by the present data.7 latex pages 5 figures. This report supercedes the unpublished reminder hep-ph/0308277. Version 2 to appear in Physics Letters B, one reference added and minor improvementsHigh Energy Physics - PhenomenologyNuclear Theorytext