NEUTRINO PHYSICS AND CALABI-YAU STRING THEORY

Properties of the heterotic string which possesses at M_pℓ E₆ symmetry in the physical sector and matter parity symmetry are discussed. If E₆ → [SU(3)]³ breaking occurs at M_pℓ followed by intermediate scale breaking to SU(3) × SU(2) × U(1) triggered by SUSY soft breaking masses, then there exists at least two (and generally more) new light SU(3) × SU(2) × U(1) singlets. These new particles interact with leptons and Higgs bosons giving rise to neutrino masses, neutrino oscillations and lepton number violating decays μ → eγ, τ → μγ accessible to experimental detection. Constraints for the Gepner three generation model to be phenomenologically viable are given.