Transcript Dark Matter and Dark Energy - University of California

Neutrino Physics III
Hitoshi Murayama
University of Pisa
February 26, 2003
Outline
•
•
•
•
•
•
Three Generations
LSND
Implications of Neutrino Mass
Why do we exist?
Models of flavor
Conclusions
2
Three Generations
MNS matrix
• Standard parameterization of MakiNakagawa-Sakata matrix for 3 generations
U MNS
1

 


U e1

 U  1

U  1
c 23
 s 23
Ue2
U2
U 2
U e 3 

U  3 

U  3 
 c13

s 23 

i
c 23  s13 e
atmospheric
s13 e
 i
1
c13
???
 c
 12
 s12


s12
c12




1 
solar
4
Three-generation
• Solar & atmospheric n oscillations easily accommodated
within three generations
• sin22q23 near maximal, Dm2atm ~ 310–3eV2
• sin22q12 large, Dm2solar ~ 510–5eV2
• sin22q13 < 0.05 from CHOOZ, Palo Verde
• Because of small sin22q13, solar & atmospheric n
oscillations almost decouple
• Need to know sin22q13,
and mass hierarchy
5
Raised More Questions
• Why do neutrinos have
mass at all?
• Why so small?
• We have seen mass
differences. What are the
masses?
Wn~mn/15eV
• Do we need a fourth
neutrino?
• Are neutrinos and antineutrinos the same?
• How do we extend the Standard
Model to incorporate massive
neutrinos?
6
3-flavor mixing
• If m1 and m2 not very different, it reduces to
the 2-flavor problem
*
n  n  , t  U  1U  1 e
*
U  2 U  2 e

2
im 2 t / 2 p
*
2
im 1 t / 2 p
*
 U  3U  3 e

*
 U  1U  1  U  2 U  2 e
*
 U  3U  3 e
e
i
2
im 1 t / 2 p
2
im 1 t / 2 p
*
2
im 3 t / 2 p
*
 U  3U  3 e
 U  3U  3 e
2
im 3 t / 2 p
2
im 3 t / 2 p
2
 im 2 t / 2 p

im
t
/
2
p
1
3
sin q  e
 e



7

When is 3-flavor important?
n n  ,t
2


*
*
U  iU  iU  j U  j
e

2
2

i m i  m j t / 2 p
i, j

  2  e U  iU  iU  j U  j  sin
*
*
2
2

i, j
*
*

t
4p
i, j
   m U  iU  iU  j U  j sin
2
mi  m j
2
2
mi  m j
t
2p
When all masses significantly different
Anti-neutrinos: UU*, the last term flips sign
Possible CP violation
8
CP Violation
P (n e  n  )  P ( n e  n  ) 
D m 2 
12
sin  sin 
L sin
 4 E

2
16 s12 c12 s13 c13 s 23 c 23
D m 2 
D m 2 
13
23

L sin 
L 
 4 E

 4 E

• Possible only if:
– Dm122, s12 large enough (LMA)
– q13 large enough
9
10
LSND
11

p 




 e n en
n


  n
ne ?

ne p  e n
12
3.3s Signal
• Excess positron events
over calculated BG
P (n  ne )
 (0.264  0.067  0.045 )%
13
Mini-BooNE
• LSND unconfirmed
• Neutrino beam from
Fermilab booster
• Settles the issue of
LSND evidence
• Started data taking the
summer 2002
14
LSND Affects
SN1987A neutrino burst
• Kamiokande’s 11 events:
– 1st event is forward
may well be ne from deleptonization burst
(p e-  n ne to become neutron
star)
_
– Later events most likely ne
• LSND parameters cause complete MSW
conversion of
nenif light side (ne lighter)
_
_
nenif dark side (ne heavier)
• Either mass spectrum disfavored
HM, Yanagida
15
LSND Affects
SN1987A neutrino burst
HM, Yanagida
16
Sterile Neutrino
• LSND, atmospheric and
solar neutrino oscillation
signals
• 3+1 or 2+2 spectrum?
Dm2LSND ~ eV2
Dm2atm ~ 310–3eV2
Dm2solar < 10–3eV2
 Can’t be accommodated with
3 neutrinos
 Need a sterile neutrino
New type of neutrino with no
weak interaction
17
Sterile Neutrino getting tight
• 3+1 spectrum: sin22qLSND=4|U4e|2|U4|2
– |U4|2 can’t be big because of CDHS, SK U/D
– |U4e|2 can’t be big because of Bugey
– Marginally allowed
• 2+2 spectrum: past fits preferred
– Atmospheric mostly nn
– Solar mostly nens (or vice versa)
– Now pretty much ruled out
(Barger et al, Giunti et al, Gonzalez-Garcia et al, Strumia, Maltoni et al)
18
WMAP
Maltoni, Schwetz, Tortola, Valle
hep-ph/0209368
19
CPT Violation?
“A desperate remedy…”
• LSND evidence:
anti-neutrinos
• Solar evidence:
neutrinos
• If neutrinos and anti-neutrinos
have different mass spectra,
atmospheric, solar, LSND
accommodated without a sterile
neutrino
(HM, Yanagida)
(Barenboim, Lykken, et al)
Best fit to data before KamLAND
(Strumia)
20
KamLAND impact
• However, now there is an
evidence for “solar” oscillation
in anti-neutrinos from
KamLAND
• Barenboim, Borissov, Lykken:
evidence for atmospheric
neutrino oscillation is
dominantly for neutrinos. Antineutrinos suppressed by a factor
of 3.
• Not a great fit (Strumia)
• New CPT violation:
21
CPT Theorem
• Based on three assumptions:
– Locality
– Lorentz invariance
– Hermiticity of Hamiltonian
• Violation of any one of them:
big impact on fundamental physics
• Neutrino mass: tiny effect from high-scale physics
– Non-local Hamiltonian? (HM, Yanagida)
– Brane world? (Barenboim, Borissov, Lykken, Smirnov)
– Dipole Field Theory? (Bergman, Dasgupta, Ganor, Karczmarek, Rajesh)
22
Implications on Experiments
• Mini-BooNE experiment will not see oscillation in
neutrino mode, but will in anti-neutrino mode
• Because KamLAND is consistent with LMA,
atmospheric neutrino oscillation relies on Dm2LSND ~
eV2 (not a great fit)
• Katrin may see
_ endpoint spectrum distortion in
t3He+e–+ne
 We’ll see!
23
Maybe even more surprises
in neutrinos!
24
Mass Spectrum
What do we do now?
25
Two ways to go
(1) Dirac Neutrinos:
– There are new
particles, right-handed
neutrinos, after all
– Why haven’t we seen
them?
– Right-handed neutrino
must be very very
weakly coupled
– Why?
26
Extra Dimension
• All charged particles are on a 3-brane
• Right-handed neutrinos SM gauge singlet
 Can propagate in the “bulk”
• Makes neutrino mass small
(Arkani-Hamed, Dimopoulos, Dvali, March-Russell;
Dienes, Dudas, Gherghetta)
• Barbieri-Strumia: SN1987A constraint
“Warped” extra dimension (Grossman, Neubert)
• Or SUSY breaking
(Arkani-Hamed, Hall, HM, Smith, Weiner;
Arkani-Hamed, Kaplan, HM, Nomura)

4
d q
*
S
M
( LH
u
N)
27
Two ways to go
(2) Majorana Neutrinos:
– There are no new light
particles
– What if I pass a
neutrino and look
back?
– Must be right-handed
anti-neutrinos
– No fundamental
distinction between
neutrinos and antineutrinos!
28
Seesaw Mechanism
• Why is neutrino mass so small?
• Need right-handed neutrinos to generate
neutrino mass , but nR SM neutral
n L

n R 
m D
m D n L 
 
M n R 
2
mn 
mD
M
 m D
To obtain m3~(Dm2atm)1/2, mD~mt, M3~1015GeV (GUT!)
29
Grand Unification
• electromagnetic, weak, and
strong forces have very
different strengths
• But their strengths become the
same at 1016 GeV if
supersymmetry
• To obtain
m3~(Dm2atm)1/2, mD~mt
 M3~1015GeV!
M3
Neutrino mass may be
probing unification:
Einstein’s dream
30
Why do we exist?
Matter Anti-matter Asymmetry
Big-Bang Nucleosynthesis
Cosmic Microwave Background
WMAP

nB
n

 1.0

 4.7  0.8  10
 10
 5.0  0.5   10
 10
(Thuan, Izatov)
(Burles, Nollett, Turner)
32
Matter and Anti-Matter
Early Universe
10,000,000,001
Matter
10,000,000,000
Anti-matter
33
Matter and Anti-Matter
Current Universe
us
1
Matter
Anti-matter
The Great Annihilation
34
Sakharov’s Conditions
for Baryogenesis
• Necessary requirements for baryogenesis:
– Baryon number violation
– CP violation
– Non-equilibrium
 G(DB>0) > G(DB<0)
• Possible new consequences in
– Proton decay
– CP violation
35
Original GUT Baryogenesis
• GUT necessarily breaks B.
• A GUT-scale particle X decays out-of-equilibrium
with direct CP violation
B( X  q)  B( X  q )
• Now direct CP violation observed: e’!
B(K
0


   )  B( K
0


   )
• But keeps B–L0  “anomaly washout”
• Also monopole problem
36
Electroweak Anomaly
• Actually, SM converts
L to B.
– In Early Universe (T >
200GeV), W/Z are
massless and fluctuate
in W/Z plasma
– Energy levels for lefthanded quarks/leptons
fluctuate correspondingly
DL=DQ=DQ=DQ=DB=1  DB–L)=0
37
Two Main Directions
• BL0 gets washed out at T>TEW~174GeV
• Electroweak Baryogenesis (Kuzmin, Rubakov, Shaposhnikov)
– Start with B=L=0
– First-order phase transition  non-equilibrium
– Try to create BL0
• Leptogenesis (Fukugita, Yanagida)
– Create L0 somehow from L-violation
– Anomaly partially converts L to B
38
Leptogenesis
• You generate Lepton Asymmetry first.
• Generate L from the direct CP violation in right-handed
neutrino decay
*
*
G ( N 1  n i H )  G ( N 1  n i H )  Im( h1 j h1k hlk h lj )
• L gets converted to B via EW anomaly
 More matter than anti-matter
 We have survived “The Great Annihilation”
39
Does Leptogenesis Work?
• Much more details worked out
(Buchmüller, Plümacher; Pilaftsis)
• ~1010 GeV nR OK
• Some tension with supersymmetry because
of unwanted gravitino overproduction
• Ways around: coherent oscillation of righthanded sneutrino (HM, Yanagida+Hamaguchi)
40
Does Leptogenesis Work?
• Some tension with
supersymmetry:
– unwanted gravitino
overproduction
– gravitino decay
dissociates light nuclei
– destroys the success of
Big-Bang
Nucleosynthesis
– Need TRH<109 GeV
(Kawasaki, Kohri, Moroi)
41
Leptogenesis Works!
• Coherent oscillation of righthanded sneutrino
(Bose-Einstein condensate) (HM,
Yanagida+Hamaguchi)
– Inflation ends with a large
sneutrino amplitude
– Starts oscillation
– dominates the Universe
– Its decay produces asymmetry
– Consistent with observed
oscillation pattern
– isocurvature perturbation at
WMAP? (Moroi, HM)
nB
s
~e
Tdecay
M1
2
Tdecay
h13
n B 
~  
arg 2
 s obs 10 6 GeV
h 33
42
Can we prove it experimentally?
• We studied this question at Snowmass2001
(Ellis, Gavela, Kayser, HM, Chang)
– Unfortunately, no: it is difficult to reconstruct relevant
CP-violating phases from neutrino data
• But: we will probably believe it if
– 0nbb found
– CP violation found in neutrino oscillation
– EW baryogenesis ruled out
Archeological evidences
43
Models of Flavor
Question of Flavor
• What distinguishes different generations?
– Same gauge quantum numbers, yet different
• Hierarchy with small mixings:
 Need some ordered structure
• Probably a hidden flavor quantum number
 Need flavor symmetry
– Flavor symmetry must allow top Yukawa
– Other Yukawas forbidden
– Small symmetry breaking generates small Yukawas
45
Fermion Mass Relation
in SU(5)
• down- and lepton-Yukawa couplings come
from the same SU(5) operator 10 5* H
• Fermion mass relation
mb= m, ms = m, md = me @MGUT
Reality:
mb≈ m, 3ms ≈ m, md ≈ 3me @MGUT
• Not bad! (small correction compared to
inter-generational splitting ~20–200)
46
Broken Flavor Symmetry
• Flavor symmetry broken by a VEV e~0.02
• SU(5)-like:
Mu
– 10(Q, uR, eR) (+2, +1, 0)
– 5*(L, dR) (+1, +1, +1)
e 4 e 3 e 2 
e 3



3
2
2
~ e
e
e , M d ~ e
 2


e
1 
e
 e
e
3
e
2
e
3 
3

e
e


2
2
e , M l ~ e

 3
e 
e
e
2
e
2
e
2
e 

e 

e 
– mu:mc:mt ~ md2:ms2:mb2 ~ me2:m2:m2 ~e4: e2 :1
47
Not bad!
• mb~ m, ms ~ m, md ~ me @MGUT
• mu:mc:mt ~ md2:ms2:mb2 ~ me2:m2:m2
48
New Data from Neutrinos
• Neutrinos are already providing significant new
information about flavor symmetries
• If LMA, all mixing except Ue3 large
e

big

 big

big
big
big
big
small n e 
 
big n  
 
big n  
2
D m solar
2
D m atm
~ 0.01 – 0.2
– Two mass splittings not very different
– Atmospheric mixing maximal
– Any new symmetry or structure behind it?
49
Is There A Structure
In Neutrino Masses & Mixings?
• Monte Carlo random complex 33 matrices
with seesaw mechanism
(Hall, HM, Weiner; Haba, HM)
50
Anarchy
• No particular structure in neutrino mass matrix
– All three angles large
– CP violation O(1)
– Ratio of two mass splittings just right for LMA
• Three out of four distributions OK
– Reasonable
 Underlying symmetries don’t distinguish 3 neutrinos.
51
q13 in Anarchy
•
•
•
•
•
q13 cannot be too small if
anarchy
How often can “large”
angle fluctuate down to
the CHOOZ limit?
Kolmogorov–Smirnov
test: 12%
sin2 2q13>0.004 (3s)
If so, CP violation
observable at long
baseline experiment
52
Anarchy is Peaceful
• Anarchy (Miriam-Webster):
“A utopian society of individuals who enjoy complete freedom without
government”
• Peaceful ideology that neutrinos work together based on
their good will
• Predicts large mixings, LMA, large CP violation
• sin22q13 just below the bound
• Ideal for VLBL experiments
• Wants globalization!
53
Program:
More flavor parameters
• Squarks, sleptons also come with mass matrices
• Off-diagonal elements violate flavor: suppressed by flavor symmetries
2
M Q˜
~
2
M L˜
 1

~  e
 2
e
e
1
e
2
e 

e 

1 
• Look for flavor violation due to SUSY loops
• Then look for patterns to identify symmetries
 Repeat Gell-Mann–Okubo!
• Need to know SUSY masses
54
To Figure It Out…
• Models differ in flavor quantum number
assignments
• Need data on sin22q13, solar neutrinos, CP
violation, B-physics, LFV, EWSB, proton decay
• Archaeology
• We will learn insight on origin of flavor by
studying as many fossils as possible
– cf. CMBR in cosmology
55
More Fossils:
Lepton Flavor Violation
• Neutrino oscillation
 lepton family number is not conserved!
–
–
–
–
–
Any tests using charged leptons?
Top quark unified with leptons
Slepton masses split in up- or neutrino-basis
Causes lepton-flavor violation (Barbieri, Hall)
predict B(), B(e), e at interesting (or toolarge) levels
56
Barbieri, Hall,
Strumia
57
More Fossils:
Quark Flavor Violation
• Now also large mixing
between n and n
– (n, bR) and (n, sR)
unified in SU(5)
– Doesn’t show up in CKM
matrix
– But can show up among
squarks
– CP violation in Bs mixing
(BsJ/y)
– Addt’l CP violation in
penguin bs (BdKs)
(Chang, Masiero, HM)
58
Conclusions
Conclusions
• Historic era in neutrino physics
• Oscillation in atmospheric neutrino: an
unexpected discovery, strong evidence for
neutrino mass
• Decades-long problem in solar neutrinos now
being resolved
• A lot more to learn in the near future
• Interesting connections to cosmology, astrophysics
• We’d like to know how to build the new Standard
Model!
60