2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/46866The mass problem in particle physics and its impact for other fields is discussed. While the problem of the nuclear masses has been resolved within the QCD framework, many parameters of the ``Standard Model'' are related to the fermion sector. The origin of the fermion masses remains unresolved. We discuss attempts to explain the observed hierarchical features of the mass spectrum by a symmetry, relating the mass eigenvalues to the flavor mixing angles.9 latex pagesHigh Energy Physics - Phenomenologytext