A' Yu' Smirnov

1
Neutrinos

discovering
new physics world
A. Yu. Smirnov
International Centre for Theoretical Physics,
Trieste, Italy Institute for Nuclear Research,
RAS, Moscow, Russia
Ljubljana, January 9, 2008
2
Neutrinos

• - elusive,
• - very small,
• extremely light

fermions spin 1/2
Qg 0 Qc 0
Only the weak and gravitational interactions
unique feature - neutrality
r lt 10-16 cm
Enormous and largely unexplored potential for
applications
Key tool in our understanding micro as well as
macro world
Particular role in nature

• - one of the most abundant
• component in the Universe
• related to the Dark energy?

Construction of the Standard model and beyond
3
... new physics world

Since 1998
Discovery of neutrino
mass and mixing
Applications
Underlying physics
4

Discovery of neutrino
masses and mixing
5
Neutrino masses

Kinematical methods
It took more than 70 years since
106 105 104 103 102 101 100 10-1 10 -2
me
Pauli
W. Paulis original idea 1930 of the order
of electron mass
Fermi
E. Fermis estimations, 1934 m lt 0.1 me
mn , eV
Bergkvist
ITEP
Zurich
Los Alamos
Troitzk, Mainz
to conclude
KATRIN
at least one neutrino mass is in the range
(0.05 0.20) eV
Work of several generations of theoreticians
and experimentalists
2008
10-7 me , 10-10 mp , 10-12mt
6
50 years ago...

B. Pontecorvo
Mesonium and antimesonium
Zh. Eksp.Teor. Fiz. 33, 549 (1957) Sov. Phys.
JETP 6, 429 (1957) translation
mentioned a possibility of neutrino mixing and
oscillations
Results of Wu experiment, 1957 Parity violation
? V-A theory, two-component massless neutrino
Oscillations imply non-zero masses (mass
squared differences) and mixing
7
Neutrino mixing

Mass eigenstates
Flavor neutrino states
n2
n1
n3
nm
nt
ne
m1
m2
m3
m
e
t
- correspond to certain charged leptons
Mixing
- interact in pairs

• flavor characteristic
• of interaction

Flavor states
Mass eigenstates

n ? p e- ne
nf UPMNS nmass
p ? m nm
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Mixing angles
ne
nm
nt

Ue32
Moduli of mixing elements are paremeterization
independent
Um32
Ut32
n3
tan2q12 Ue22 / Ue12
Dm2atm
sin2q13 Ue32
mass
Ue22
n2
tan2q23 Um32 / Ut32
n1
Dm2sun
Ue12
Normal mass hierarchy
Rotation in 3D space
nf UPMNS nmass
Dm2atm Dm232 m23 - m22
UPMNS U23 Id U13 I-d U12
Dm2sun Dm221 m22 - m21
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Solar
KamLAND

neutrinos
Atmospheric
Masses
MINOS
neutrinos
Mixing
K2K
CHOOZ
Cosmology
Double beta decay
MiniBooNE
Supernova neutrinos
Beta decay
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Determination of parameters

Oscillations in vacuum and in matter
Mass and mixing parameters
Modification of neutrino properties (flavors)
Dmij2 mi2 - mj2
qij
Adiabatic conversion in matter - the MSW effect
Measurements
Two effects of neutrino propagation
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Oscillations
Periodic (in time and distance) process of
transformation (partial or complete) of one
neutrino species into another one

ne
ne
ne
ne
nm
nm
nm
1.0
survival probability
0.5
0
distance
Occurs in vacuum or in medium with constant
density
12
Refraction
L. Wolfenstein, 1978
for ne nm

ne
e
Elastic forward scattering
Potentials
Ve, Vm
W
ne
V 10-13 eV inside the Earth for E 10 MeV
e
difference of potentials
Ve- Vm 2 GFne
Refraction index
n - 1 V / p
10-20 inside the Earth
lt 10-18 inside the Sun
n 1
10-6 inside the neutron star
Neutrino optics
13
Adiabatic conversion -

the MSW - effect
Medium with slowly varying density
survival probability
distance
Flavor of neutrino state follows density change
14
Solar Neutrinos
4p 2e- ? 4He 2ne 26.73 MeV
electron neutrinos are produced
Adiabatic conversion
F 6 1010 cm-2 c-1
total flux at the Earth
n
Oscillations in matter of the Earth
r (150 0) g/cc
15
Homestake

GNO
SAGE
GALLEX
Kamiokande
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SuperKamiokande

50 kt water Cherenkov detector
n e -gt n e
SNO
Detect effect of adiabatic conversion
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BOREXINO

7Be neutrinos, E 0.862 MeV
300t
n e -gt n e
47.5 live days fiducial mass 87.9 t (liquid
scintillator)
rate 47 /- 7 (st) /-12(syst)
count/(day 100ton)
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KamLAND
Kamioka Large Anti-Neutrino Detector
Reactor long baseline experiment 150 - 210 km
ne p ? e n
Epr gt 2.6 MeV
Data total rate energy spectrum of events
Vacuum oscillations
Detection of the Geo-neutrinos
Epr gt 1.3 MeV
1 kton of Liquid scintillator
19
Atmospheric neutrinos
Parametric effects in nm - ne oscillations for
core crossing trajectories

atmosphere
ne
p
p
m
nm
N
e
cosmic rays
nm
nm - ne oscillations in matter
n
core
At low energies
r Fm /Fe 2
nm - nt vacuum oscillations
n
mantle
Detector
SuperKamikande Soudan MACRO, MINOS
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K2K

KEK to Kamioka
nm -gt nm
Vacuum oscillations
SuperKamiokande
21
MINOS
Main Injector Neutrino Oscillation Search

LBL Fermilab SOUDAN mine
Near detector (1km) 1 kton
Far detector (735 km) 5400 t, steel, sampling
calorimeter
Beam 120 GeV protons 2.5 1020 p/year -gt 1 - 10
GeV neutrinos
Vacuum oscillations
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Cosmological bounds

Large scale structure of the Universe
SDSS
23
Double beta decay

Heidelberg-Moscow experiment
76Ge ? 76Se e e
neutrinoless double beta decay
Fifth detector
Evidence of the effect Cosmology? If 2b 0n ?
mechanism?
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Spectrum
ne
nm
nt

?
n2
n3
Dm2sun
n1
?
mass
mass
Dm2atm
Dm2atm
n2
Dm2sun
n1
n3
Inverted mass hierarchy
Normal mass hierarchy

• - 1-3 mixing
• mass hierarchy
• CP violation phase
• absolute scale of neutrino mass
• additional neutrino states

Unknown
nf UPMNS nmass
UPMNS U23 Id U13 I-d U12
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Leptons versus quarks

zero 1-3 mixing?
?
n3
t
maximal mixing
mass
mass
tri-maximal
n2
c
n1
u
large 1-2 mixing
Quarks
Leptons
small mixing
nf UPMNS nmass
Ud UCKM U
U (u, c, t)
combination of upper-quarks produced with a given
down quark
26

What is behind?
Understanding the results
27
Salient features

Small
Strange
related?
mixing
neutrino
pattern
masses
New symmetries?
indicate that most probably we are touching
something qualitatively new
28
Comments

Physics behind neutrino mass and mixing is not
yet identified
Something beyond the standard model
Data show both order and
some degree of randomness ? no simple
explanations is expected
Different pieces of data testify for different
underlying physics
and illustrations
29

On cross-roads
30
Main line

1. Smallness of neutrino mass is related to the
Majorana nature of neutrinos
P. Minkowski T. Yanagida M. Gell-Mann, P. Ramond,
R. Slansky S. L. Glashow R.N. Mohapatra, G.
Senjanovic
Majorana neutrino antineutrino
allowed by neutrality of neutrinos
mn
2. See-saw scenario
n
mD
(normal)2 Large
MR
small
N
small masses of usual neutrinos normal
electroweak scale 100 GeV Large masses of
Right neutrino or some VEV

The same mechanism explains large lepton mixing?
31
Grand unification?

RH neutrino components have large Majorana mass
1 MR
mn - mDT mD
in the presence of mixing
MGUT
MR
MGUT2 MPl
MGUT 1016 GeV - possible scale of
unification of EM
, strong and weak interactions
Neutrino mass as an evidence of Grand
Unification ?

• ? lepton asymmetry
• baryon asymmetry
• of the Universe

Leptogenesis the CP-violating out of
equilibrium decay
N ? l H
32
Scales of new physics

Grand
Low scale
unification
mechanisms
Planck
M3 MGUT
Intermediate
EW scale?
scale
kev-scale mechanisms?
scale
With many O(100) RH neutrinos
1019 GeV
1016 GeV
10-6 GeV
1010 GeV
25 orders of magnitude!
33
Quark-Lepton Complementarity

Lepton mixing bi-maximal mixing quark
mixing
A.S. M. Raidal H. Minakata
ql12 k qq12 p/4
ql23 qq23 p/4
k 2-1/2 or 1
qualitatively
2-3 leptonic mixing is close to maximal because
2-3 quark mixing is small
1-2 leptonic mixing deviates from maximal
substantially because 1-2 quark mixing is
relatively large
34
Possible implications

Lepton mixing bi-maximal mixing quark
mixing
Quark-lepton symmetry
unification
Existence of structure which produces bi-maximal
mixing
See-saw? Properties of the RH neutrinos
Vquarks I, Vleptons Vbm m1 m2 0
In the lowest approximation
35
Tri/bimaximal mixing
L. Wolfenstein
P. F. Harrison D. H. Perkins W. G. Scott

2/3 1/3 0 - 1/6 1/3 1/2
1/6 - 1/3 1/2
Utbm
n3 is bi-maximally mixed
n2 is tri-maximally mixed
- maximal 2-3 mixing - zero 1-3 mixing - no
CP-violation
sin2q12 1/3
Utbm U23(p/4)U12
36
Possible implications

Utbm Umag U13(p/4)
E. Ma
1 1 1 Umag 1 w w2
1 w2 w
w exp (-2ip/3)
tetrahedron
Symmetry
symmetry group of even permutations of 4
elements
A4
representations 3, 1, 1, 1
Other possibilities
T7 , D4 , S4 , D(3n2 )
Relation to masses? No analogy in the quark
sector? Unification is problematic?
Extended higgs sector, Auxiliary symmetries,
vacuum alignment
37
1-2 mixing

QLCl
p/4 - qC
tbm
QLCn
KamLADN SNO, 2007
Maltoni et al 2007
3s
2s
3s
SNO (2n)
2s
1s
Strumia-Vissani
99
90
Fogli et al
3s
Gonzalez-Garcia, Maltoni
1s
q12
29 31 33 35 37 39
q12 qC p/4
Utbm Utm Um13
UQLC1 UC Ubm
give almost same 12 mixing
38
Real or accidental?

Tri-bimaximal mixing
Q-L-complementarity
Maximal 2-3 mixing
Small 1-3 mixing
Koide relation
From numerology to fundamental principles?
39
Something

completely different?
Extra Dimensions
New mechanism of generation of small Dirac
masses overlap suppression
Related to the fact that the right-handed
components of neutrinos have no SM interactions
40
...in large flat extra D

Small Dirac masses due to overlap
suppression
3D brane
Mass term m fL fR h. c.
If left and right components are localized
differently in extra dimensions ? suppression
fL
wave functions
m e fL fR h. c.
overlap
fR
amount of overlap in extra D
Arkani-Hamed, Dvali, Dimopoulos
0
R
Large extra D 3D brane
RH neutrinos propagate in the bulk
A Yu Smirnov
41
...in warped extra D

Grossman Neubert Huber, Shafi...
Visible brane
Hidden brane
In Randall -Sundrum (non-factorizable metric)
fR0
fL0
Setting 1 extra D S 1/Z2
wave functions
overlap
p
0
f
RH neutrinos - bulk zero mode localized on the
hidden brane
A Yu Smirnov
42
... on the fat brane

Arkani-Hamed, Schmaltz
3D brane
fR
fR
wave functions
overlap
fL
fL
A Yu Smirnov
43
What's next?

New measurements type of spectrum
(quasi-degenerate hierarchical),
type of hierarchy, majorana
nature 1-3
mixing, deviation of 2-3 mixing from maximal,
CP-violation
phases tests
of predictions of particular models
This may discriminate various possibilities but
not lead to final answer.
LHC, other non-neutrino experiments may check low
scale models, mechanisms, test a context
Theory two points of view
Nothing fundamental accidental interplay of
many unrelated factors results of some
complicated evolution (like planetary system?)
The hope is that neutrinos will uncover something
simple and illuminating before we will be lost
in the string landscape
44

Applications
Toward neutrino technologies
45
The earth density profile

A.M. Dziewonski D.L Anderson 1981
PREM model
Fe
inner core
Si
outer core
(phase transitions in silicate minerals)
transition zone
lower mantle
crust
upper mantle
liquid
solid
46
The earth portraits

ne ? nt
- peaks - ridges - valleys - saddle points
zenith angle
oscillograms
E. Akhmedov M. Maltoni, A.S,
Contours of constant oscillation probability
47
Measuring oscillograms

Study of various oscillation effects
e.g. parametric enhancement of oscillations
Goals
Determination of neutrino parameters
- 1-3 mixing - mass hierarchy normal
vs. inverted - CP violation phase
Tomography of the Earth resolution
4pE/Dm2 gt 100 km
Tools
Accelerator
Atmospheric
beams
neutrinos
E 0.5 -- few GeV, 10 30 GeV
cos qn lt 0.3 fixed
E 0.1 104 GeV, cos qn -1 -- 0
Detectors gt 1 Mt TITAND?
Superbeams, beta beams muon factories
48
Supernovae monitoring

shock wave
20 years SN1987A
Diffusion
Flavor conversion inside the star
Propagation in vacuum
Oscillations Inside the Earth
49
Shock wave effects
R.C. Schirato, G.M. Fuller, astro-ph/0205390
Influences neutrino conversion if sin2q13 gt 10-5
Adiabaticity breaking in shock wave front ?
Adiabaticy violation wave.
Time - energy
The effects are in the neutrino (antineutrino)
for normal (inverted) hierarchy
h - resonance
change the number of events
wave of softening of spectrum
delayed Earth matter effect
Density profile with shock wave propagation at
various times post-bounce
50
Shock wave effects

Window of broken adiabaticity
R. Tomas, et al., JCAP 0409, 015 2004
time energy connection
Average energy of events at SK
Antineutrino survival probability at different
moments of time
In window spectrum change H ? MS
51
Monitoring shock wave by neutrinos

Studying effects of the shock wave on the
properties of neutrino burst one can get (in
principle) information on
time of propagation velocity of propagation
shock wave revival time density gradient in
the front size of the front
Steep front breaks adiabaticity or make its
violation stronger, - after passing can be
restored again - influence transitions
Can shed some light on mechanism of explosion
52

Conclusions
53
Last 10 years breakthrough - discovery
of neutrino mass - determination of the
dominant structure of lepton mixing
discovery of two large mixings angles -
establishing strong difference of quark and
lepton mass/mixing.

It seems we are touching something really new.
In spite of plenty of proposed models and
approaches, no unique and convincing scenario of
physics beyond the standard model has been
found.
Applications and neutrino technologies
geophysics, earth tomography search for oil and
minerals, control of atomic reactors, etc. etc..