Neutrino Masses and Lepton Flavor Physics

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Neutrino Masses and Lepton Flavor Physics

• K.S. Babu
• Department of Physics, Oklahoma State University

PHENO 03 Madison, Wisconsin, May 5, 2003
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Outline

• Neutrino Oscillation Results
• Interpreting Data
• Patterns of Neutrino Mass Spectrum
• Neutrinoless Double Beta Decay (bb)0n Tests
• Theoretical Modeling
• Large Neutrino Mixing
• Unified Quark-Lepton Description
• Lepton Flavor Violation
• Rare Decays t?mg, m?eg
• Lepton Dipole Moments
• Conclusions

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Solar Neutrino Oscillations
Gonzalez-Garcia et al. (2003)
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Atmosphere Neutrino Oscillations
Maltoni, et al. hep-ph/0207227
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LSND
Aguilar, et. al hep-exp/0104049
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Patterns of Neutrino Mass Spectrum
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Neutrino Mixing versus Quark Mixing
Leptons
Quarks
Disparity a challenge for Quark-Lepton unified
theories.
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(bb)0n and Pattern of Neutrino Masses
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(meV)
Pascoli, Petcov, Rodejohann, hep-ph/0212113
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Neutrino Masses and the Scale of New Physics
Very Close to the GUT scale.
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Gauge Coupling Unification in MSSM
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Structure of Matter Multiplets
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Large Neutrino Mixing with Lopsided Mass Matrices
Quark and Lepton Mass hierarchy
This motivates
KSB and S. Barr, 1995
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Example of Lopsided Mass Matrices
Gogoladze, Wang, KSB, 2003
Discrete ZN Gauge Symmetry
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Lopsided Mass Matrix Model in SO(10)
S.Barr and KSB,2002
PREDICTIONS
10 Parameters vs. 20 Observables
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FIT
Buras, et al
Georgi-Jarlskog
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Neutrino Mass Textures
Fukugita, Tanimoto, Yanagida, 2003
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A4 Symmetry and Quasi-degenerate Neutrino
E. Ma, 2002 E. Ma, J. Valle, KSB, 2002
With Arbitrary Soft A4 Breaking
With Complex parameters, arg(Ue3) p/2
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Electric Dipole Moments
Violates CP
Electron
Neutron
Phases in SUSY breaking sector contribute to EDM.
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SUSY Contributions
A, B are complex in MSSM
Effective SUSY Phase
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If parity is realized asymptotically, EDM will
arise only through non-hermiticity induced by RGE.
Subject to experimental tests
Dutta, Mohapatra, KB (2001)
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Lepton Flavor Violation and Neutrino Mass

• Seesaw mechanism naturally explains small n-mass.

Current neutrino-oscillation data suggests
Flavor change in neutrino-sector
Flavor change in charged leptons
In standard model with Seesaw, leptonic flavor
changing is very tiny.
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In Supersymmetric Standard model
For
nR active
flavor violation in neutrino sector Transmitted
to Sleptons
Borzumati, Masiero (1986) Hall, Kostelecky, Raby
(1986) Hisano, et al (1995)
SUSY Seesaw Mechanism
If B-L is gauged, MR must arise through Yukawa
couplings.
Flavor violation may reside entirely in f or
entirely in Yn
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If flavor violation occurs only in Dirac Yukawa
Yn (with mSUGRA)
If flavor violation occurs only in f (Majorana
LFV)
LFV in the two scenarios are comparable. More
detailed study is needed.
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Neutrino Fit
For Majorana LFV scenario, take
Dutta, Mohapatra, KB 2002
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For Dirac LFV scenario
Same neutrino oscillation parameters as in
Majorona LFV
The two scenarios differ in predictions for
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Dirac LFV
F. Deppisch, et al, hep-ph/0206122
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Majorana LFV
Dutta, Mohapatra, KB (2002)
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Correlation between LFV and B?fKs
Hisano and Shimizu, hep-ph/0303071
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LFV in SUSY SO(10)
Masiero, Vempati and Vives, hep-ph/0209303
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Conclusions

• Neutrino Experiments pinning down oscillation
  parameters.
• Neutrinoless double beta decay can discriminate
  between various mass patterns.
• Large Neutrino Mixing can arise from Unified
  theories through lopsided mass matrices.
• Lepton Flavor Violation t?mg, m?eg, and EDMs
  within reach of experiments.