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.
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