Freiburg 2008 – scientific programme

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T: Fachverband Teilchenphysik

T 18: Neutrinophysik (Theorie)

T 18.1: Talk

Friday, March 7, 2008, 14:00–14:15, Peterhof-HS 4

Quark-Lepton Complementarity from Discrete Flavor Symmetries — •Florian Plentinger, Gerhart Seidl, and Walter Winter — Institut für Theoretische Physik und Astrophysik, Universität Würzburg, D-97074 Würzburg, Germany

We present numerous simple models for fermion masses realizing quark-lepton complementarity, i.e., the solar mixing angle θ₁₂ obeys the sum-rule θ₁₂+θ_C≈π/4, where θ_C is the Cabbibo angle. As flavor symmetries, we use products of cyclic groups. The fermion mass hierarchies are generated by higher-dimension operators via the Froggatt-Nielsen mechanism. Neutrino masses emerge exclusively from the usual type-I seesaw mechanism. We focus on solutions that can naturally give close to tri-bimaximal lepton mixing with a very small reactor angle θ₁₃≪θ_C. Hierarchical fermion mass ratios and the mixing angles are predicted as powers of a single parameter of the order of θ_C. These models are rather general in the sense that large mixings can come from the charged leptons and/or neutrinos. Moreover, in the neutrino sector, both left- and right-handed neutrinos can mix maximally. This could be the result of quark-lepton unification in grand unified theories.