2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/188133The Goldberger--Treiman relation for heavy--light systems is derived in the context of a quark model. As a paradigmatic example, the case of ${\bar D}\to {\bar D}' π$ is studied in detail. The fundamental role played by the pion two-component wave function, in the context of the Salpeter equation, is emphasized.6 pages, 2 figures, version to appear in Phys. Rev. DHigh Energy Physics - Phenomenologytext