Neutrino Democracy And Other Phenomenology From 5D SO(10)

Abstract

We present a five dimensional supersymmetric SO(10) model compactified on an orbifold $S^{(1)}/Z_2\tm Z_2'$. The gauge symmetry $G_{422}\equiv SU(4)_c\tm SU(2)_L\tm SU(2)_R$, realized on one of the fixed points (branes), is spontaneously broken to the MSSM via the higgs mechanism. Employing a flavor ${\cal U}(1)$ symmetry and suitably extending the 'matter' sector enables us to understand large mixings in the neutrino sector via a democratic approach, versus the small CKM mixings. A residual ${\cal R}$-symmetry on $G_{422}$ brane helps eliminate the troublesome dimension five nucleon decay, while the ${\cal U}(1)$ symmetry plays an essential role in suppressing dimension six decay. For rare leptonic decays we expect ${\rm BR}(\mu \to e\ga)\sim {\rm BR}(\tau \to \mu \ga)\sim {\rm BR}(\tau \to e\ga)$.