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Models of Neutrino Mass G.G.Ross, IPPP December 2005 Origin of mass and mass hierarchy What do we learn from the mixing angles?

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Presentation on theme: "Models of Neutrino Mass G.G.Ross, IPPP December 2005 Origin of mass and mass hierarchy What do we learn from the mixing angles?"— Presentation transcript:

1 Models of Neutrino Mass G.G.Ross, IPPP December 2005 Origin of mass and mass hierarchy What do we learn from the mixing angles?

2 Origin of Neutrino masses Dirac or Majorana?

3 Origin of Neutrino masses Dirac or Majorana? Weinberg 1979

4 Minkowski mechanism Origin of Neutrino masses Dirac or Majorana?

5 Weinberg 1979 Origin of Neutrino masses Dirac or Majorana?

6 New space dimensions Closed string 11D propagation Graviton, Modulini Open string SM states } Flux spreading Arkani Hamed, Dimopoulos, March Russell Dienes,Farragi In 4D small Dirac masses can arise through higher dimension operators Abel, Dedes, Tamvakis Dirac or Majorana?

7 Neutrino mass and dark energy Quintessence field Symmetry needed to keep it light CP violating field of neutrino mass matrix? Barbieri, Hall, Oliver, Strumia Mass varying neutrinos energy in A At finite density : Fardon, Nelson, Weiner

8 … dimension of operator … order of radiative corrections Hierarchy Structure Can get normal, inverted or degenerate structures (NB Radiative corrections can split precise degeneracies unless protected by symmetry)

9 Unravelling the origin of mass….. …difficult (impossible) unless we are lucky! 10 0 10 -1 10 10 -2 10 -3 10 -4 eV Mixing Bi-Tri Maximal Mixing … Harrison, Perkins, Scott ansatz Non Abelian Structure? Many possibilities, many parameters… Small in quark sector, large in lepton sector?

10 Tri-Bi-Maximal mixing

11 Discrete non Abelian family symmetry Bi-maximal But what about the charged lepton sector Need complete theory…

12 “ See-saw ” with sequential domination SRHD King Two ingredients : (Discrete) Non-Abelian family symmetry small Vacuum alignment King, GGR, Varzielas

13 Vacuum alignment Altarelli,Feruglio King,GGR,Varzielas

14 Summary Origin of mass and mass hierarchy - Many possibilities for both Majorana and Dirac masses : Heavy see-saw, light see-saw, bare Dirac, radiative generation, radiative running, running masses…dark energy - All patterns of mass possible : normal, inverted, degenerate What do we learn from the mixing angles? -Hints at an underlying (spontaneously broken) family symmetry? SO(10)XSU(3)? Unified theory of quark, charged lepton and neutrino masses with related textures

15 Spontaneous symmetry breaking c.f. Georgi-Jarskog only terms allowed by G I de Medeiros, GGR King, Vives, Velasco Sevilla… Common texture zero

16 Summary Origin of mass and mass hierarchy - Many possibilities for both Majorana and Dirac masses : Heavy see-saw, light see-saw, bare Dirac, radiative generation, radiative running, running masses…dark energy - All patterns of mass possible : normal, inverted, degenerate What do we learn from the mixing angles? -Hints at an underlying (spontaneously broken) family symmetry? SO(10)XSU(3)? Unified theory of quark, charged lepton and neutrino masses with related textures - A discrete non-Abelian subgroup can give vacuum alignment needed for bi-tri-maximal mixing


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