Fermion Masses and Mixings in GUTs with Non-Canonical U(1)_Y

Understand

We 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.