\theta_13, Rare Processes and Proton Decay in Flipped SU(5)

Abstract

We consider an extended flipped SU(5) model, supplemented by a flavor ${\cal U}(1)$ symmetry, which yields bi-large neutrino mixings, charged fermion mass hierarchies and CKM mixings. The third leptonic mixing angle $\te_{13}$ turns out to lie close to 0.07, and neutrino CP violation can be estimated from the observed baryon asymmetry. For lepton flavor violating processes we find the branching ratios, ${\rm BR}(\mu \to e\ga)\sim {\rm BR}(\tau \to e \ga) \sim 10^{-4}\cdot {\rm BR}(\tau \to \mu \ga) \stackrel{<}{_\sim}5\cdot 10^{-14}$. The proton lifetime $\tau_{p\to \pi^0 e^{+}}\simeq 10^{34}-10^{36}$ yrs.