Fourth Generation and Dark MFourth Generation and Dark Matteratter

Yu-Feng ZhouYu-Feng Zhou

State Key Laboratory of Theoretical Physics,State Key Laboratory of Theoretical Physics, Kavli Institute for Theoretical Physics China,Kavli Institute for Theoretical Physics China,

Institute of Theoretical Physics,Institute of Theoretical Physics,Chinese Academy of SciencesChinese Academy of Sciences

arXiv:1110.2930arXiv:1110.2930 2011.11.24, 科大交叉中心

outline Introduction

Overview on current DM searches Neutrinos as DM components The 4th generation models

A 4th generation model with Majorana neutrino DM The 4th generation with U(1)’_F. Correlation between relic density and event rate in direct det

ection searches Numerical results

Conclusions

DM revealed from gravitational effects

Gravitational curves

Strong lensing

Weak lensing

Large scale structure

CMB

Bullet clusters

Little is known about DM Massive: from gravitation. Stable: lifetime longer than the Universe Electro-magnetic neutral: dark, but can annihilate into photons (i

ndirectly) Non-baryonic

MACHOs: disfavored by micro-lensing D/H from BBN CMB

Non-relativistic motion ( from simulations ) Cold DM ： substructure, halo core Warm DM more favorable ?

No DM candidate in the Standard Model The standard model (SM)

Particles: Quarks: u,d,c,s,t,b (charged) Leptons: electron (charged, stable ), muon, tau (charged, unstable) neutrino (neutral, stable) Gauges bosons: W, Z0 (neutral, unstable), gamma (neutral, massless) (Higgs boson): H0 (neutral, unstable )

Interactions : SU(3)xSU(2)xU(1)

Problem with SM neutrino Problem with SM neutrino DMDM

Abundance of hot relicAbundance of hot relic

CMB anisotropies: CMB anisotropies: Structure formationStructure formation

neutrino erase fluctuations below ~40 Mpc, imply a top-neutrino erase fluctuations below ~40 Mpc, imply a top-down structure formation.down structure formation.

Neutrino cannot be the main part of DM, We must go beyond the SM !

The WIMPs miracle The WIMPs miracle Thermal freeze out: Thermal freeze out: the origin of the origin of

speciesspecies

Weakly Interacting Massive Particles (WIMPs)

• Particle physics independently predicts WIMPs

• WIMPs have just the right relic density

• WIMPs are testable by the current exp.

Search for non-gravitational effects ?

Satellite

underground

Cherenkov telescope balloon

collider

Hints of DM ? the cosmic-ray lepton anomalies

PAMELA, Nature 458, 607 (2009)

ATIC, Nature, 456, 2008,362-365

Fermi-LAT, Phys.Rev.Lett.102:181101,2009

PAMELA

FERMIFERMI

ATIC

Constraints from cosmic gamma-rays

Fermi-LAT, Phys.Rev.Lett.103:251101, 2009

Dugger et.al, arXiv:1009.5988Abdo, et.al, arXiv:1002.4415

DM annihilation/decay constrained by the nullresults on cosmic gamma-rays

Dark matter direct searches

DAMACDMS-II

CoGeNT

CRESST-II

Xenon100

Explanations• Inelastic scattering ?• Isospin-violating DM ?• Velocity suppressed interaction• Momentum dependent scattering• Resonant scattering

Uncertainties• halo DM velocity distribution• Quenching factors• Channeling effects• ......

M.Farina, etal, 1107.0715J.Kopp, t. Schwetz, J. Zupan,1110.2721

Stability of DM Using extra symmetries

motivated to evade phenomenological constraints R-Parity: MSSM, LSP KK-Parity: UED, LKP T-Parity: Little higgs,

motivated by DM Z_2: SM+scalar DM U(1)’: SM+fermoin DM

Using the known symmetries SU(2): Minimal DM model: SM + scalar/fermion with high repr

esentation, SU(2) “pion” P, CP: LR symmetric model + scalar

Scalar DM protected by P/CP in LR models Adding gauge-singlet in to the LR model

P- and CP-transformations

spontaneous CP violation assumed

W.L.Guo, Y.L.Wu, YFZ,Phys.Rev.D79:055015(2009) Phys.Rev.D82:095004(2010) Phys.Rev.D81:075014(2010)

Residual Z_2

The relic density of DM Thermal: decouple from thermal equi

librium Nonthermal: never reached thermal e

quilibrium (super weak)Nonthermal generation of DM gravitational interaction decay of unstable particles

Late decay may affect BBN, CMB DM may get warm

by transitions from other particles

Thermal DM density enhanced by late decay of unstable states

Thermal DM density enhanced by other DMs

J.L.Feng 2004

Z.P.Liu,Y.L. Wu, YFZ, Eur.Phys.J.C71:1749(2011)

Zupan, etal, 2009

Neutrinos as DM candidates/components Very light SM neutrinos (hot DM)CMB bound:Disfavored by large scale structure formation

KeV sterile neutrinos (warm DM)Less substructure, favored by observationsLife-time longer than the UniverseNon-thermal generationConstraints: X-ray, BBN, Ly-alpha,…hard to detect directly ?

Heavy neutrinos (cold DM)Heavy active Dirac/Majorana neutrinocannot make up the whole DM (not necessary in multi-DM models !)Heavy sterile neutrino ?

2 0.0067(90% )h CL

GUT scale

eV

KeV

EW scale

hot DM

warm DM

cold DM?

DM ?

A 4th generation model with neutrino DM SM4: Simplest extension to the SM.

New sources of CP violation6 real parameters, 3 phases in CKM4Large CP violation possible Effective Hamiltonian

4 44 4 4 4

4 4

, , , , ( ),L LR R R R

L L

uSM u d v e

d e

4cs cb

ts tb

ub

cb

tb

t d t s t b

ud us ub

t

cdCKM

td

b

V

V

V

V V V

V V VV

V V

V V V V

V

1 1 2 2( )2

u u u c tFeff u i i c i i t i i

GC O C O C O C O OH C

0

Can help in explaning the CP puzzle:

( ) ( ) (14.4 2.9)%

CP CP CP

K

A A K A K

W.S.Hou, 0803.1234

A.Soni, 0807.1871

Constraints on the SM4 4th generation quarksLHC:

Tevatron:

4

4 4

4

4 4

assuming mass spliting less than

GeV,assuming

335

fr

:

o

GeV

8 m3 5 W

u d

u

d

m Wq

m m d W

um

tm

4

4

4 4

4 4

from searching for 3 ,

from searching for

450 GeV

490 GeV 3

T

T

u

d

m

m

u u WbWb b j E

d d WtWt b jE

SM higgs with 4th familyLHC ruled out:

120GeV 600GeVHm

EW precision test:

Mass difference between u_4 and d_4 have to be small

Assuming 4-3 transition and 100% Br

G. Kribs etal, 0706.3718J.Erler,P.Langacker,1003.3211

R. Contino,A. Koryot

Constraints on the SM4 leptons 4th generation leptons

4th generation neutrinos Unstable neutrinos

Stable neutrinos -> weaken EWPT bounds, dark matter ?

4 44 from100. 8GeVe e Wm

4

4

(unstable Dirac(101.3,101.5,90.3)GeV

(89.5,90.7,80.5)

)

(unstaG beV le Majorana)

m

m

4 (stable D45.0(39 irac(Ma.5) jorGeV ana))m

The 4th generation leptons must have quite different nature

4 ( , , )e W

A 4th generation model with stable neutrinos

A 4th generation U(1)’ model

Gauge interaction

Anomaly-free assignments

, ,, , , , ( 1, , 4),iR aiL iL

iL iL iR iR iRiL i

bL

uq u d e i

d e

(1)( ) (1)2 Y FS UU U

4 4

4 4

charges

, ,

, ,

6

)

2

1

3

(

3 q

L

L

q

F

i i

i i

a b

L

L

Q Q

Q

U

u d

Q

Q

e e

u

Q

d

3 2

4 4

2

1

2

2

1

[ (1) ] ,[ (3) ] ,[ ]

1) vector-like int eraction

2)

(1) 0

(1) [ (1) ] 0

[ (2) ] (

due to ( ) 0 and ( ) 0

3) from 0 an 0

1

d

) 0

qL qR L R

qi Lii

C

i

F F

Y F

L F

Y Y Y

U SU gravity U

U

Q Q

U

Y

U

SU

Anomalies canceled between generations

New interactions Interactions

The 4x4 CKM matrix is block diagonal -> no mixing at tree level

Mass of Z’ from U(1)’ breaking

† †

4 4 4

( ) ( ) ( ) ( )

1 1( , 1,2,3) ( , , ) H.c

2

.2

i i a a b bd u eij iL iR ij iL iR ij iL iR ij iL iR

m c m cij iR a jR R b R a b

f i D f D D D D

Y q Hd Y q Hu Y He Y He

Y i j Y V H

L

,

2 2 2 2 2 2

/ 2

( ),

small suppresses ,

can evade severe LHC bounds

a a b

Z F a a b b

F

v

m g Q v Q v

g Z

229

2 2

2 2 2 2 2

muon 2

3.9 1012

lead to a bound

1.4 10 GeV

F

Z

a a b b

g

mga

m

Q v Q v

YFZ, arXiv:110.2930

Dark matter in the model Possible dark matter- Lightest active neutrino (~eV)

- Light sterile neutrinos (~KeV)

- Lightest 4th neutrino (~100 GeV)

- Neutral 4th bound-states ?

A multi-component DM model?

The 4th heavy Majorana neutrino as DM component

- allow

- assumption on halo DM

- nontrivial correlation between relic density and the event-rate of direct detection.

- very predictive, constrained by the current exp., clear prediction for SI scattering

21 3 ), ( ,L LL

1 2 3, ,R R R

44 ,L R

1 1,DM

r

11

0

,DM

r

0.11i DM

4th Neutrino mass matrix

Mass eigenstates (the lightest one is stable: U(1)’ protected )

Interactions with Z and SM higgs

0,D

D M

mm

m m

( ) ( )1 2( ), ,m c m cL L R L L Ri c s s c

2tan 2 .D

M

m

m 1 2, and .D D

s cm m m m

c s

2 5 2 511 1 2 2 1 22 ,

4cosNCW

gc s ics Z

L

2 2 5 011 1 2 2 1 2( ) .Y

H

m ccs cs i c s h

v s

L

Neutrino masses and interaction

Annihilation channels

21

21 12 2 4

1 2 1

1( 4 ) ,

8 ( / ) m

sv ds s m sK

m TK m T T

Thermally averaged cross section

Annihilation cross-sections Annihilation channels

2 2 2 2 2

2 2 2 2

0 0

0 0 0 0

4

2 4

1) For / 2, is dominant

2) For , chenn

( ) suppressed

|

,

,

el opens

3) For , chennel opens

4) For , , ch

| suppresse

enn

d

els

F V A

F W Z

Z

W

Z

H

m m ff

m m W W

m m Z Z

m m Z h

v G m v C C c

v G m c

h

s

h

v D

open

5) For , chennel openstm m tt

Different from Dirac neutrino DM- ff_bar channels are helicity and velocity suppressed- WW chanel is velocity suppressed- Zh more important

Relic density of heavy neutrino DM

Relic density

No upper bound on neutrino mass

Majorana neutrino can make up O(10%) of DM at 100 GeV, O(1%) at 200 GeV.

LEPexcluded

2 0.11DMh 9 12

* 2

1.07 10 GeV,

Fpl x

hv

g M dxx

strong mass and mixing angle dependence YFZ, arXiv:110.2930

SI cross section Event rate rescaled

Xenon ruled out mass range 55-175 GeV

Correlation - Low halo density and large SI cross s

ection all related to large Yukawa coupling-> cancellation

-week mixing angle/mass dependencesPrediction:

can be tested soon

11

0

,DM

r

LEPexcluded

44 2 for 175 Ge1.5 10 VcmSI m

SI SI

(mass dependent)

mass-dependence canceled

Relic density SI scattering

YFZ, arXiv:110.2930

SD cross section for DM-proton Event rate follow the relic density SIMPLE ruled out mass range

50-150 GeV, compatible with Xenon100 on SI cross section

Prediction

Can be reached by indirect search exp. SuperK and IceCube. The current SuperK/IceCube bounds are model dependent.

22 232 1,SD

N F n p p n n

JG a S a S

J

.2F

u d s

Gd d d

39 2 for 3 10 175 Gc eVmp m

Relic densityRelic density SI scattering

SD cross section for DM-neutron

Scattering off proton and neutron are similar

much weaker bounds compared with DM-proton case.

The Xenon10 ruled out60-120 GeV

YFZ, arXiv:110.2930

Conclusions Heavy stable neutrino as a cold DM component is highly testable

in direct detection experiments even it contribute to a small fraction of the total DM relic density

We consider a 4th generation model with an anomaly-free U(1) gauge symmetry which keep the heavy 4th Majorana neutrino stable. The models is less constrained by the current LHC data.

The Xenon100 data constrain the mass of the 4th neutrino to be heavier than 175 GeV. For heavier neutrino DM, the prediction for SI cross section is 1.5x10^-44cm^2 which is insensitive to the neutrino mass due to the correlation between relic density and the SI cross section.

The prediction for SD cross section is within the reach of SuperK and IceCube.