2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/49704The leptonic decay constant of the pseudoscalar mesons a calculated by use of the relativistic constituent quark model constructed on the point form of Poincare-covariant quantum mechanics. We discuss the role relativistic corrections for decay constants of pseudoscalar mesons with heavy quarks. We consider the heavy mass limit of decay constant for two-particle system with equal masses.Talk given at NPCS'98,Minsk,Belarus,1998. To be published in the proceedings. 4 pagesHigh Energy Physics - Phenomenologytext