2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/205635We discuss fermion masses and mixings in models derived from orbifold GUTs such that gauge coupling unification is achieved without low energy supersymmetry by utilizing a non-canonical U(1)_Y. A gauged U(1)_X flavor symmetry plays an essential role, and the Green-Schwarz mechanism is invoked in anomaly cancellations. Models containing vector-like particles with masses close to M_{GUT} are also discussed.18 pagesHigh Energy Physics - Phenomenologytext