2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/41256Barut's formula for the mass of leptons is successfully extended to quarks. A very simple non-linear scalar field model explains both the N^4 power law dependence of the mass, and the existence of a cut-off which limits the number of leptons to three and the number of quarks to five, suggesting that the mass of the sixth quark is of different origin.8 pages, 1 table, 1 figure. PACS: 12.15.Ff, 11.10High Energy Physics - Phenomenologytext