Physics Beyond the Standard Model I:Physics Beyond the Standard Model I:Neutrino Masses and the Neutrino Masses and the

Quest for UnificationQuest for Unification

K.S. BabuK.S. BabuDepartment of PhysicsDepartment of Physics

Oklahoma Center for High Energy PhysicsOklahoma Center for High Energy Physics Oklahoma State UniversityOklahoma State University

Collider and New Physics Mini-WorkshopCollider and New Physics Mini-Workshop

Natioanal Taiwan UniversityNatioanal Taiwan University

June 10, 2005June 10, 2005

OutlineOutline

Neutrino Oscillation ResultsNeutrino Oscillation ResultsInterpreting DataInterpreting Data

– Patterns of Neutrino Mass Spectrum Patterns of Neutrino Mass Spectrum – Neutrinoless Double Beta Decay Neutrinoless Double Beta Decay Tests Tests

Theoretical ModelingTheoretical Modeling– Evidence for UnificationEvidence for Unification– Large Neutrino Mixing Large Neutrino Mixing – Unified Quark-Lepton Description Unified Quark-Lepton Description

Experimental Tests Experimental Tests – Rare Decays Rare Decays →→→→ee – Lepton Dipole Moments Lepton Dipole Moments – Proton DecayProton Decay

ConclusionsConclusions

Building blocks of matter and carriers of forces

A Brief History of Neutrinos• Postulated by Pauli as a desperate measure to restore

momentum and energy conservation in beta decay (1930)• Electron type neutrino discovered by Reines and Cowan in

reactor experiments (1956)• Muon type neutrino produced in accelerators by Lederman,

Schwartz, Steinberger et al (1962)• LEP experiments measure N(nu) = 2.994 +-0.012 (1991-

2002)• Neutrinos from the Sun detected by Davis et al (1968)• Neutrinos from Supernova 1987A detected in US and Japan• Neutrino oscillations discovered in atmospheric neutrinos

[IMB, Kamiokonde (1988), SuperKamiokande (1998)]• Solar neutrino deficit confirmed by various experiments and

interpreted as evidence for neutrino oscillations (1968 –)

Solar Neutrinos

•

Gonzalez-Garcia et al. (2003)

Solar Neutrino Oscillations

Atmospheric Neutrinos

L/E Dependence of Atmospheric Neutrinos

Maltoni, et al. hep-ph/0207227

Atmosphere Neutrino Oscillations

SuperKamiokande detector

Aguilar, et. al hep-exp/0104049

LSND

Minkowski (1977)Yanagida (1979)Gell-Mann, Ramond, Slansky (1979)Mohapatra, Senjanovic (1980)

Patterns of Neutrino Mass SpectrumPatterns of Neutrino Mass Spectrum

Neutrino Mixing versus Quark MixingNeutrino Mixing versus Quark Mixing

Leptons

Quarks

Disparity a challenge for Quark-Lepton unified theories.

and Pattern of Neutrino Masses and Pattern of Neutrino Masses

Pascoli, Petcov, Rodejohann, hep-ph/0212113

(meV)

Neutrino Masses and the Scale of New PhysicsNeutrino Masses and the Scale of New Physics

Very Close to the GUT scale.

from atmospheric neutrino oscillation data

Leptogenesis via R decay explains cosmological baryon asymmetry

Evolution of Gauge Couplings Evolution of Gauge Couplings

Standard Model Supersymmetry

K. Dienes, Phys. Rept. (1997)

SUSY SpectrumSUSY Spectrum

SM ParticlesSM Particles SUSY PartnersSUSY Partners

Spin = 1/2 Spin = 0

Spin = 0 Spin = 1/2

Spin = 1 Spin = 1/2

Structure of Matter MultipletsStructure of Matter Multiplets

Matter Unification Matter Unification in 16 of SO(10)in 16 of SO(10)

Other Evidences for UnificationOther Evidences for Unification

Anomaly freedom automatic in many GUTsAnomaly freedom automatic in many GUTs

Electric charge quantizationElectric charge quantization

Nonzero neutrino masses required in many GUTsNonzero neutrino masses required in many GUTs

Baryon number violation natural in GUTs – needed Baryon number violation natural in GUTs – needed

for generating cosmological baryon asymmetryfor generating cosmological baryon asymmetry

works well for 3rd familyworks well for 3rd family

GUT Gauge GroupsGUT Gauge Groups

• SU(5)

• SO(10)

• E6

• E8

• …

• [SU(3)][SU(3)]33

• [SU(5)][SU(5)]22

• [SU(3)][SU(3)]44

• ……

SU(5) GUTSU(5) GUT

Matter multiplets:

Higgs:

Yukawa Couplings

Contain color triplets

MSSM Higgs doublets have color triplet partners in GUTs. MSSM Higgs doublets have color triplet partners in GUTs.

must remain lightmust remain light

must have GUT scale mass to prevent rapid must have GUT scale mass to prevent rapid proton decayproton decay

Doublet-triplet splitting

Even if color triplets have GUT scale Even if color triplets have GUT scale mass, d=5 proton decay is problematic.mass, d=5 proton decay is problematic.

Symmetry BreakingSymmetry Breaking

Doublet-triplet splitting in SU(5)

The GOODThe GOOD

(1)(1) Predicts unification of couplingsPredicts unification of couplings

(2)(2) Uses economic Higgs sectorUses economic Higgs sector

The BADThe BAD

(1)(1) Unnatural fine tuningUnnatural fine tuning

(2)(2) Large proton decay rateLarge proton decay rate

FINE-TUNED TO O(MW)

Nucleon Decay in SUSY GUTsNucleon Decay in SUSY GUTs

Gauge boson ExchangeGauge boson Exchange

Higgsino ExchangeHiggsino Exchange Sakai, Yanagida (1982)

Weinberg (1982)

SO(10) GUTSO(10) GUT

Quarks and leptons ~{16i}

Contains R and Seesaw mechanism

Fits the atmospheric neutrino data well

Small Higgs rep small threshold corrections for gauge couplings

R-parity not automatic (needs a Z2 symmetry)

Model with Non-renormalizable Yukawa Couplings

Higgs:

Matter Unification Matter Unification in 16 of SO(10)in 16 of SO(10)

SUSY SO(10)

B-L VEV gives mass to triplets only (DIMOPOULOS-WILCZEK)

If 10H only couples to fermions, no d=5 proton decay

Doublets from and light

4 doublets, unification upset

Add mass term for 10’H

Realistic SO(10) ModelRealistic SO(10) ModelPati, Wilczek, KB (1998)

PredictionsPredictions

Large Neutrino Mixing with Lopsided Mass MatricesLarge Neutrino Mixing with Lopsided Mass Matrices

Quark and Lepton Mass hierarchy:

This motivates:

Albright, KSB and Barr, 1998

Sato and Yanagida, 1998

Irges, Lavignac, Ramond, 1998

Altarelli, Feruglio, 1998

KSB and S. Barr, 1995

Example of Lopsided Mass MatricesExample of Lopsided Mass MatricesGogoladze, Wang, KSB, 2003

Discrete ZN Gauge Symmetry

Neutrino Mass TexturesNeutrino Mass Textures

Fukugita, Tanimoto, Yanagida, 2003

AA4 4 Symmetry and Quasi-degenerate NeutrinoSymmetry and Quasi-degenerate Neutrino

E. Ma, 2002

E. Ma, J. Valle, KSB, 2002

With Arbitrary Soft A4 Breaking

With Complex parameters, arg(Ue3) = /2

Seesaw mechanism naturally explains small Seesaw mechanism naturally explains small mass.mass.

Current neutrino-oscillation data suggestsCurrent neutrino-oscillation data suggests

Flavor change in neutrino-sectorFlavor change in neutrino-sector

Flavor change in charged leptonsFlavor change in charged leptons

In standard model with Seesaw, leptonic flavor changing is very tiny.In standard model with Seesaw, leptonic flavor changing is very tiny.

Lepton Flavor Violation and Neutrino MassLepton Flavor Violation and Neutrino Mass

In Supersymmetric Standard modelIn Supersymmetric Standard model

ForFor R activeactive

SUSY Seesaw MechanismSUSY Seesaw Mechanism

If If B-L B-L is gauged, Mis gauged, MRR must arise through Yukawa couplings. must arise through Yukawa couplings.

Flavor violation may reside entirely in f or entirely in Flavor violation may reside entirely in f or entirely in YY

flavor violation in neutrino sector Transmitted to Sleptonsflavor violation in neutrino sector Transmitted to SleptonsBorzumati, Masiero (1986)

Hall, Kostelecky, Raby (1986)

Hisano et. al., (1995)

F. Deppisch, et al, hep-ph/0206122

Dirac LFV

If flavor violation occurs only inIf flavor violation occurs only in f ((Majorana LFVMajorana LFV))

If flavor violation occurs only in Dirac Yukawa If flavor violation occurs only in Dirac Yukawa YY

(with mSUGRA)(with mSUGRA)

LFV in the two scenarios are comparable.LFV in the two scenarios are comparable.

More detailed study is needed. More detailed study is needed.

Dutta, Mohapatra, KB (2002)

Majorana LFV

LFV in SUSY SO(10)LFV in SUSY SO(10)

Masiero, Vempati and Vives, hep-ph/0209303

Electric Dipole MomentsElectric Dipole Moments

Violates CPViolates CP

Electron:

Neutron:

Phases in SUSY breaking sector contribute to EDM.Phases in SUSY breaking sector contribute to EDM.

SUSY Contributions:SUSY Contributions:

A, B are complex in MSSMA, B are complex in MSSM

Effective SUSY Phase

If parity is realized asymptotically,If parity is realized asymptotically,

EDM will arise only through non-hermiticity induced by RGE.EDM will arise only through non-hermiticity induced by RGE.

Subject to experimental testsSubject to experimental tests

Dutta, Mohapatra, KB (2001)

ConclusionsConclusions

• Neutrino Experiments pinning down oscillation parametersNeutrino Experiments pinning down oscillation parameters• Neutrinoless double beta decay can discriminate between Neutrinoless double beta decay can discriminate between

various mass patternsvarious mass patterns• Unification of different forces very attractive theoreticalyUnification of different forces very attractive theoreticaly• Large neutrino mixing can arise from Unified theories Large neutrino mixing can arise from Unified theories

through lopsided mass matricesthrough lopsided mass matrices• Discovery of supersymmetry highly anticipated at LHCDiscovery of supersymmetry highly anticipated at LHC• Lepton Flavor Violation Lepton Flavor Violation →→→→eeand EDMs within and EDMs within

reach of experiments reach of experiments • Direct observation of proton decay is the hallmark of Direct observation of proton decay is the hallmark of

unification paradigmunification paradigm