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Theoretical Implications of neutrino oscillations

How many light neutrinos?. Spectral pattern?. Near degeneracy, hierarchy, inverted hierarchy?. Theoretical Implications of neutrino oscillations. Crucial questions :. G. Ross, Imperial College, July 02. Why so light?. Dirac, Majorana?. Underlying origin?. Family symmetry? Unification?.

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Theoretical Implications of neutrino oscillations

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  1. How many light neutrinos? Spectral pattern? Near degeneracy, hierarchy, inverted hierarchy? Theoretical Implications of neutrino oscillations Crucial questions : G. Ross, Imperial College, July 02 Why so light? Dirac, Majorana? Underlying origin? Family symmetry? Unification?

  2. 3 : How many light neutrinos? … protected by symmetry 4.. : e.g. SUSY new neutral fermions Masses not small but can generate neutrino masses via mixing with via R-parity violation m=0 through chiral symmetry Modulini Compactification radius

  3. New space dimensions Radiative mass generation Why so light? Symmetry breaking { High scale : GUT breaking Low scale : RP violation, See-saw Valle et al

  4. New space dimensions Closed string 11D propagation Graviton, Modulini Open string SM states } Flux spreading Dirac mass …. Could also be Majorana mass in bulk

  5. See-saw Majorana mass : c.f. GUT scale MX=3.1016GeV Double see-saw

  6. 10 100 10-1 10-2 10-3 10-4 eV Degenerate Normal Inverted 4-neutrino Spectral pattern?

  7. 10 100 10-1 10-2 10-3 10-4 eV Near degeneracy To generate the degeneracy need a family symmetry – ensures it is stable against radiative corrections Barbieri, Hall, Kane, Strumia, GGR • Large mixing angles natural • Cosmologically interesting abundance possible

  8. 10 100 10-1 10-2 10-3 10-4 eV Near degeneracy To generate the degeneracy need a family symmetry – ensures it is stable against radiative corrections Pseudo Dirac gives suppression

  9. See-saw : } 9 params 18 parameters 10 100 10-1 Atmospheric 10-2 10-3 10-4 King Altarelli, Ferugio, Masina Smirnov eV SRHD Normal hierarchy “Bottom-up” – no complicated conspiracy between matrix elements of MD, MM Lavignac, Masina, Savoy Ml diagonal

  10. Atmospheric 10 100 10-1 10-2 10-3 10-4 eV SRHD Solar? Hierarchical DRHD Close to bound

  11. 10 100 10-1 Atmospheric 10-2 10-3 10-4 eV Ml diagonal SRHD Solar? Degenerate Pseudo Dirac + similar form for MD Near maximal U12

  12. Pseudo Dirac 10 100 10-1 10-2 10-3 10-4 eV Inverted hierarchy { Small Lavignac et al See-saw :

  13. Underlying origin? . Unification : } RH quark mixing } LH lepton mixing

  14. DRHD ? Large mixings Underlying origin? . Unification : { SO(10) SU(2)L,R

  15. -12 -9 -6 -3 0 3 GeV Mixing DATA : Masses ?

  16. Mass matrix determination Near equality – large mixing Symmetric fit Asymmetric fit

  17. King, GGR, Velasco Sevilla

  18. Charged lepton structure in good agreement with experiment + + + Georgi Jarlskog

  19. Neutrinos

  20. νs - Near bi-maximal mixing Majorana Mass “See Saw” DRHD

  21. Origin of hierarchy …Li, X, SUSY …New space dimensions …See-saw …Family symmetry Connection between quarks and leptons? SU(5), SO(10), strings Large mixing Small mixing See saw CP May be probed in ν sector SUMMARY The new data for lepton masses and mixings (and quarks) is testing our ideas for the origin of the fermion masses and mixings and raises interesting questions : Multiplicity of neutrinos? New symmetries

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