Theoretical Implications of neutrino oscillations

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Theoretical Implications of neutrino oscillations

• G. Ross, Imperial College, July 02

Crucial questions
Why so light?
Dirac, Majorana?
Underlying origin?
Family symmetry? Unification?
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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
m0 through chiral symmetry
Modulini
Compactification radius
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Why so light?
Symmetry breaking

High scale GUT breaking Low scale RP
violation,
See-saw
Valle et al
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Flux spreading
Dirac mass . Could also be Majorana mass in bulk
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Majorana mass
c.f. GUT scale MX3.1016GeV
Double see-saw
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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

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Near degeneracy
To generate the degeneracy need a family symmetry
ensures it is stable against radiative
corrections
Pseudo Dirac gives suppression
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Normal hierarchy
Bottom-up no complicated conspiracy between
matrix elements of MD, MM
Lavignac, Masina, Savoy
Ml diagonal
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SRHD
Solar?
Hierarchical
DRHD
Close to bound
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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
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Inverted hierarchy

Small
Lavignac et al
See-saw
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.
Unification

RH quark mixing

LH lepton mixing
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.
Unification

SO(10)
SU(2)L,R
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DATA Masses
?
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Mass matrix determination
Near equality large mixing
Symmetric fit
Asymmetric fit
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Charged lepton structure in good agreement with
experiment



Georgi Jarlskog
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Neutrinos
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?s - Near bi-maximal mixing
Majorana Mass
See Saw DRHD
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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