Neutrino Mass and MixingNeutrino Mass and Mixing

Workshop for Underground Experiments

and Astroparticle Physics

Feb. 16-19, 2005 Muju, Korea

Sin Kyu Kang (Seoul National University)

Workshop for Underground Experiments

and Astroparticle Physics

Feb. 16-19, 2005 Muju, Korea

Sin Kyu Kang (Seoul National University)

Contents

Evidence for Neutrino Oscillation• Atmospheric Neutrino• Solar Neutrino• Terrestrial Neutrino Phenomenology of Neutrino Mixing Proposals of Small Neutrino Masses Leptonic CP Violation

Evidence for Neutrino Oscillation• Atmospheric Neutrino• Solar Neutrino• Terrestrial Neutrino Phenomenology of Neutrino Mixing Proposals of Small Neutrino Masses Leptonic CP Violation

Evidence for Neutrino Oscillations

Cosmic Ray

, K

e

e

μ

Neutrinos from the other side of the Earth.

e

Super-Kamiokande (50,000ton water Ch. Detector)

Atmospheric Neutrino Oscillation

• SK observed flux deficit

SK Collab. hep-ex/0404034SK : L/E DependenceSK : L/E Dependence

oscillation

decoherence

decay

• SK observed an apparent oscillation dip. • Rival hypotheses such as neutrino decay and de

coherence disfavored at 3.5

Evidence for muon neutrino oscillation in an accelerator-based experiment (K2K)

(11 November 2004)

Evidence for muon neutrino oscillation in an accelerator-based experiment (K2K)

(11 November 2004)

• beam with mean E=1.3 GeV directed at SK 250 km away

• 107 observed events

• events expected without oscillation

• Best fit :

• beam with mean E=1.3 GeV directed at SK 250 km away

• 107 observed events

• events expected without oscillation

• Best fit :

μν

1210151

2 3 2m 2.8 10 eV 2sin 2 1.0

• neutrino2004

2-flavor oscillations

Oscillation Analysis Results

Kearns, neutrino2004

L / E Oscillation Analysis Result

22 2 atm

atm

mP sin sin

4E

•How the Sun burns

Solar Neutrino Oscillation

solar neutrino

observation via

e d p p e

x xd p n

x xe e

CC

NC

ES

8 B

SNO ExperimentSNO Experiment

• SNO Pure D2O Results (SNO Collab. PRL 89 (2002) )

• (SNO Collab. PRL92 (2004) )

cc(e) = 1.76 (stat.) (syst.) × 106

es(x) = 2.39 (stat.) (syst.) × 106

nc(x) = 5.09 (stat.) (syst.) × 106

+0.06

−0.05

+0.09

−0.09

+0.24

−0.23

+0.12

−0.12

+0.44

−0.43

+0.46

−0.43

cc(e) = 1.70 (stat.) (syst.) × 106

es(x) = 2.13 (stat.) (syst.) × 106

nc(x) = 4.90 (stat.) (syst.) × 106

+0.07

−0.07

+0.09

−0.10+0.29

−0.28

+0.15

−0.08+0.24

−0.24

+0.29

−0.27

Evidence for flux deficit of solar neutrinoThis anomaly can be interpreted by MSW

LMA

8 6 2 1SSM(2004) : ( B) 5.26(1 0.23) 10 cm s

SNO Salt FluxesSNO Salt FluxesSNO Pure D2O Results

SNO Pure D2O Results

• 1st result From Mar. 4 to Oct.6, 2002145.1 live days, 162 ton-year ex.Neutrino disappearence at 99.99%

• 2nd result From Mar.9 (02) to Jan 11 (04)515.1 live days, 766.3 ton-y ex.Neutrino disappearence at 99.99%

Reactor Long Baseline Experiment150 - 210 km ( Epr > 2.6 MeV )

e + p e+ + n

R 0.611 0.085(stat) 0.041(sys)

R 0.686 0.044(stat) 0.045(sys)

Evidence of Spectral Distortion (1 November 2004)

Neutrino Oscillation parameter allowed regions

2 0.6 5 20.5m 8.2 10 eV

2 0.090.07tan 0.40

Best fit

Matter Effect (Mikheyev, Smirnov, Wolfestein)

Elastic forward scattering

e e

W

ee

H0 H = H0 + V

12 1m2m

1m

m

1 e 2m

2

0cc F e e eL 2G n

H common

m2

4E

cos2 sin 2sin 2 cos2

2GFne1 0

0 0

• Distortion of E spectrum :

3 explicit signatures of MSW effect

• Distortion of E spectrum

• Observation of vacuum-dominated mixing at low E

Day/Night Effect Binned (PLB539, 179) Unbinned (PRD 69)

AND = -2.1 % (2.0 %) AND= -1.8% (1.6%)

LMA-IILMA-I

expected

observed(± 1)

LMA-II disfavored

Determination of 13

• intense and nearly pure neutrino flavor composition

( 1km, 3MeV)L E ( )e

CHOOZ CHOOZ experimentexperiment :

e p e n

2sin 2 0.16

2 3 22 10 eV m

for

• Solar and KamLAND provide information on independent of CHOOZ and atmospheric neutrino data

• Global analysis of all available data (Malton et al.) :

6.313 4.44.4 (2 )

13

4.813 7.57.5 (2 )

• Allowed regions at 90%, 95%, 99%, 3 from CHOOZ(lines), CHOOZ+solar+KamLand(colored)

Future experiments for 13

• SNO D2O data+ SK• SNO salt phase Evidence for in • KamLAND Evidence for oscillation in vacuum Confirm LMA solution

• L/E analysis in SK Evidence for oscillation

• For :

SummarySummary

e

8

e

B

Remarkable Progress since 2001

Remarkable Progress since 2001

Solar+KamLAND (Maltoni et al.’04)

Atm+K2K (Maltoni et al. ’04)

13

Three Neutrino OscillationsThree Neutrino Oscillations

13 13 12 12

23 23 12 12

23 23 13 13

1 0 0 cos 0 sin cos sin 0

0 cos sin 0 1 0 sin cos 0

0 sin cos sin 0 cos 0 0 1

i

PMNSi

e

U P

e

small

i iU Masseigenstate

Weak eigenstate

m1

m2

m3 3

2

1

Neutrino Mixing

N.H.

LBL (future)Reactor

SolarKamLAND

AtmosphericLBL

CP phase

factory

Bi-large mixing between neighboring families

(1,2) & (2,3)

The ratio

no strong mass hierarchy

Mixing between remote (1,3) families small ??

Absolute mass scale

Type of mass spectrum

Type of mass hierarchy

• What is the origin of neutrino mass ?

• Why are neutrino masses so small?

• Why is the lepton flavor mixing large and so different from quark mixing?

• Does the result of lepton mixing imply GUT ?

• Are neutrinos Dirac or Majorana?• If new light sterile neutrinos exis

t, what is their nature and underlying physics?

• Is leptonic CP violated?• Can neutrinos play a role in gener

ating our Universe?• Non-oscillating phenomena

Known & UnknownKnown & Unknown

2 221 32m / m 0.01 0.15

Theoretical QuestionsTheoretical Questions

(Guzzo, Holanda, Peres ’04 ; Friedland, Lunardini, Pena-Garay ’04) Very small flavor universality violation can lead to

suppression of ve earth regeneration shift of resonance layer in the sun

(Holanda & Smirnov ’03 ; Dev & Kumar ’04)• Upturn of the solar neutrino sepctrum at low energy Homestake lower rate of Ar-production No apparent upturn of boron neutrino spectrum explained if a light sterile neutrino exists cf.) fit to solar data : (Bahcall, Gonzalez-Garcia, Pena-Garay ’04)

Probing subleading effects

2sin 0.09(0.35)

Nonstandard interactions

Sterile neutrino mixing

Pattern of neutrino mixing

exp

0.79 0.86 0.50 0.61 0 0.16

0.24 0.52 0.44 0.69 0.63 0.79

0.26 0.52 0.47 0.71 0.60 0.77

U

2

3 1,eU

cos sin 0

sin cos 1

2 2 2

sin cos 1

2 2 2

s s

s s

s s

U

Why both mixings Large ?

45atm •In the limit•In the limit

Bi-maximal mixing

(1) Deviation from Bi-maximal mixing (Giunti & Tanimoto, ’02 Frampton, Petcov, Rodejohann ’04)

In the case of small using data :

In the case of using data

lep bimaxU U ( )U , 1 1

02 21 1 1

2 2 21 1 1

2 2 2

bimaxU

lepU ( ), ij

lepijsin

ij( 0.35)

2 2sol 12 13

2 2 3atm 23

2e3 12 13

tan 1 2 2( ) ( )

sin 2 1 4 ( )

| U | | ( ) / 2 ( ) |

lep CKMU U ,

e3

2 2sol e3 e3

2 4 4atm e3

| U | 0.162

tan 1 4 | U | 8 | U |

sin 2 1 4 1 16 | U |

23

12

13

0.19

(0.21 0.26)

0.03

2sol

2atm

0.22

tan 0.52

sin 0.96

(2) Quark-Lepton Complementary (Grand Unification) (Ramond et

al.’03, Minakata & Smirnov ’04, Raidal, Frampton & Mohapatra ’04)

Simplest Higgs structure which relates quark & lepton Yukawa matrices:

expC 12.7 exp

sol 32.6 1.6

exp expsol C 45.3 1.6

Td l

u Dirac

M M

M M

: SU(5)

: SO(10)

Dd dL d dRM U M U ,

Du uL u uRM U M U ,

Dl lL l lRM U M U , D

Dirac 0L Dirac 0RM U M U ,

D * D Tseesaw 0L Dirac 0R 0R Dirac 0L

R

1M U M U U M U

M

T0L 0LU CU TC VD V

TMNS lL 0L dR dL CKMQ Lsymmetry

U U U V U U U V

In models where Md is symmetric,

MNS CKMU U V

(3) tri/bi-maximal mixing Harrison, Perkins, Scott ’99,’02 Z.Xing,’02, He, Zee, ’03, Koide ’03 Chang, Kang, Kim ’04, Kang ’04

Origin of tri/bi-maximal mixing S3 permutation family symmetry

MNS

2 10

6 31 1 1

U6 3 2

1 1 1

6 3 2

I

22 2

e2 e3 3U 1 3, U 0, U 1 2

This symmetry supports an inverted mass hierarchy, but rather large mee shows strong violation of this symmetry.

Discrete symmetries : A4, S3, Zn, D4

U(1) : Froggatt-Nielsen Non-abelian symmetries : SU(2), SO(3), SU(3)

Dirac type : demands RH components (EW singlet), but their masses are unportected by symmetry

Majorana type : due to neutrality

Flavor Symmetry & neutrino masses

Flavor Symmetry & neutrino masses

eL L L

Do the patterns of neutrino masses and mixing reflect certain symmetry?

Generation of neutrino mass :

How small Neutrino Mass ?

• Cosmological Mass Limit :

2 0.007692.5

mh

eV

0.23(eV)m

WMAP

(1) Simplest possibility : (Yanagida, Gell-mann,Ramond, Slansky,Mohapatra, Senjanivic,’80)

cf) type II seesaw : introducing SU(2) triplet Higgs (Mohapatra & Senjanovic, ’81, Wetterich ’81)

Neutrino Majorana : can lead to and other processes

Scale of M : roughly speaking could be indication of grand unification

Why ?Why ?u,d,em m

..0

)(2

1cc

Mm

mL

R

L

D

DRLmass

Mass eigenvalues ~

0

L 2 14 1510 10 GeV

2Dm

;MM

Seesaw mechanism

Implications of Seesaw

Directly : to observe heavy RH neutrinos difficult! Indirectly : (1) and other processes

(2) RH neutrinos generate renormalization effect between M and GUT scale which modifies masses and mixing of light neutrinos

(3) If SUSY is realized, Yukawa couplings via RG give contributions to slepton mass matrix which in turn produces a number of observable effects via LFV

(4) Leptogenesis : probing Dirac Yukawa structure. it leads to bounds on lightest M

0 L 2

How to Probe seesaw ?

(2) Radiative mechanism : Zee model : excluded in its minimal version

no RH beutrino, new scalar (Frampton etal.’02, X. He ’04)

Two loop generations : (Babu ’88, Chang & Zee ’00)

no RH neutrino, new singlet scalar

SUSY with trilinear R-parity violating couplings (Hall & Suzuki, Dree et al.)c c

ijk i j k ijk i j kL L E L Q D

l

l~

q

q~

)/ln(16

)/ln(16

2~

22

*2~

22

*

bbblll mmmmmmm

,

2,H

(3) Interesting attempts in extra dimensions large EXD (ADD) :Dirac mass suppressed by the large

volume of EXD (Dienes et al ’98, ADD’02)

warped EXD (RS) : RH neutrinos can be zero modes localized on the hidden brane leading to small Dirac mass (Grossman & Neubert ’00)

(4) Combination of Seesaw & radiative generations : (Hall & Suzuki, Hempfuling,Joshipura & Novakowski, Chun et al, Chun & Kang, Jung et al.,

Kong, Hirsch et al. Valle, Grossman & Haber, Losada & Davidson)

in SUSY with tri/bi-linear R-parity violating terms tree neutrino mass generated from the seesaw

due to mixing of neutrinos with neutralinos 1-loop mass via tri-linear couplings

Probing in Future Collider Experiments

SUSY without R-parity as a theory of massive neutrinos can be testable in collider ! (Chun et al, ’99,’02,’04, Bartl et al.’03, Hirsch et al., ’01,’02,’03)

Key idea : Probing of decays of LSP (lightest SUSY particle)

Decay amplitude 0

2 3 F iG M

( )

ij i j

i i

m c

Dirac CP violation : CKM-like phase in UPMNS

measurable in neutrino oscillation if using the hierarchy

for the golden channel

and should be large should not be too small CPV phase should be large the baseline should be long enough (typically 3000 or 7000km)

Leptonic CP violation Leptonic CP violation

P( ) P( )

2 221 32m m ,

222 3121

CP

13 23 13 12

m Lm LA [P( ) P( )] 8J sin ,

2E 2E

1J cos sin 2 sin 2 sin 2 sin

8

e

221m

1213

Dirac CP violation

Conditions for observing CPV effects

I

• In matter : matter effect violates CP & CPT ( & ) in matter with costant density :

How to measure ? Reactor Experiments Super Beam :

JHF & SK ~300km neutrino factories ~3000, 7000km NuMI ~ 800km

P P P P P P P P

CP

mattCPA J

13

213sin

JHFJHF

~1GeV beamKamiokaJAERI

(Tokaimura)

0.77MW 50 GeV PS

( conventional beam)

Super-K: 22.5 kt

4MW 50 GeV PS

Hyper-K: 1000 kt

Phase-I (0.77MW + Super-Kamiokande)Phase-II (4MW+Hyper-K) ~ Phase-I 200

Plan to start in 2007

• The present neutrino experiments indicate the strong evidence for massive neutrinos

new physics beyond SM

• Small but finite neutrino masses need drastic idea to understand it

• Neutrino era is just beginning and we have long way to go…..

SummarySummary

• From CMB acoustic peaks(WMAP)+Large Scale Structure

• A Baryon Asymmetry can be generated in an expanding unive

rse if ( Sakharov) the particle interactions violate B, C & CP the evolution of the universe out of equilibrium

• Those conditions fullfiled in the CP violating, out of equilibrium decays of Ni

generating L asymmetry• L asymmetry B asymmetry

Baryon Asymmetry via LeptogenesisBaryon Asymmetry via Leptogenesis

CMB 10B BB

n n(6.3 0.3) 10

n

iNl( l )

( ) sphaleron

Leptogenesis (Fukugita & Yanagida ’86)

(Buchmuller et al.,Bari)

interference between tree level and (vertex+self energy) 1-loop diagrams:

barring RH neutrino degeneracy & strong phase cancellations:

2 22 i i

1 D D i1 V S2 2 2i 2,3D D 11 1 1

M M1Im[(m m ) ] f f

8 v (m m ) M M

max 21 1 1 1 1 j1(M ) (m m , ), D D 211

1 j j11

m mm m

M

2 2j j1

j2 21 1 j1 max 1 1 j1

atm 1

m Im

(m ,m , ) (m ,m , ) 1m m

max 61 atm 11 1 2 10

M m M3(M ) 10

16 v 10 GeV

CP asymmetry

(Davidson & Ibarra ’02, Buchmuller et al.)• The evolution of particle number densities in the early universe determined by solving Boltzmann equation• The final B asymmetry :

• From the condition :

• For

sph fB B L

aN

f 2B L 1 1 1

3N (z) (z;m ,M ,m )

4

2 2B 1 1 110 (m ,M ,m )

max CMBB B

CMB8 1B

1 10atm

0.05eVM 6.4 10 GeV

6 10 m

sol 1 atmm m m

101M (1.5 10) 10 GeV 9 10

iT (4 10 2 10 )GeV

Lower bound on lightest heavy neutrino mass

• Requirement ,

the domain for shirnks to zero yields upper limits on mi

•Contours of constant for the indicated values of in the plane (for NH) (Buchmuller et al. ’02)

maxB

m1 1(m ,M )

Upper bound on light neutrino masses :

2 2 2 21 2 3m m m m

max CMBB B

m 0.2eV

1 2

3

m ,m 0.11eV

m 0.12eV

2 2 2atm 3 2

2 2 2sol 2 1

m m m

m m m

Leptogenesis in SUSY• Gravitino problem BBN constraints on the abundance of gravitino for 0.1 ~ 1 TeV yield the bound (Kawasaki et al.’04)

incompatible with bound from leptogenesis !!

• To avoid gravitino problem: Non-thermal leptogenesis

(Giudice et al. Asaka , Kawasaki et al.)

Heavy gravitino scenarioanomaly mediation (Ibe et al.’04)

Gravitino LSP scenario

• Alternatives to avoid :• Soft Leptogenesis : using soft breaking terms as source

of L-violations which do not lead to seesaw neutrino masses

(Grossman et al., D’ambrosio et al., Boubekeur et al., Allahverdi et al., E.J.Chun)

• Resonant Leptogenesis (Pilaftsis)

L-asymmetry is resonantly enhanced through the mixing of nearly degenerate heavy Majorana neutrinos (~TeV)

• Various models for Low Scale Leptogenesis

6 9RT (10 10 )GeV

Connection bewteen low energy CP violation and leptogenesis

• In minimal seesaw with two heavy Majorana neutrinos

(Glashow, Frampton, Yanagida)

mD contains 3 phases

1( ) ( 1 3; )

21,2 c

Li Dij Rj Rj j RjL m N N M jN i

4 ( , ) ( ) ( ) J P P 2

1 12 11Im[( ) ] /( ) D D D Dm m m m

Existence of a correlationbetween

1J &

(Endo,Kaneko,Kang,Morozumi,Tanimoto) PRL89(2002)

• Solar + KamLAND

• (K. Inoue, NOW04)

2 0.6 5 20.5m 8.2 10 eV

2 0.09

0.07tan 0.40

Absolute Scale of Mass

Absolute Scale of Mass

From the oscillation result

From

WMAP

2h 31m m 0.04eV

0

2ee ek k

k

m U m

0m 0.23eV

• pe+0, K+, etc– Atmospheric

neutrino main background

• Cosmic rays isotropic– Atmospheric

neutrino up-down symmetric

Neutrino mass & flavor spectra

normal inverted

Neutrino Mixing

• U : Pontecorvo-Maki-Nakagawa-Sakata (PMNS) mixing matrix

Mass Spectrum & MixingMass Spectrum & Mixing

For unitary matrix Mixing angles : n 2, 3, 4

CP Phases : n 2, 3, 4 Dirac : 0 1 3

Majorana :

e

1

1

2

2

3

3

0.79 0.86 0.50 0.61 0.0 0.16

0.24 0.52 0.44 0.69 0.63 0.79

0.26 0.52 0.47 0.71 0.60 0.77

i iU nn

1n(n 1)

2 1 63

1(n 1)(n 2)

2

1n(n 1)

2 1 3 6