Transcript Where can neutrino physics lead us?

Neutrino Physics
Hitoshi Murayama (Berkeley+IPMU)
NNN 2007, Hamamatsu
Oct 3, 2007
Outline
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Past: Why Neutrinos?
Present: Era of Revolution
Near Future: Bright Prospect
Big Questions: Need Synergies
Astrophysical Probe
Conclusion
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Past
Why Neutrinos?
Probe to High Energies
• Effects of physics beyond the SM as
effective operators
• Can be classified systematically (Weinberg)
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Unique Role of Neutrino Mass
• Lowest order effect of physics at short distances
• Tiny effect (mn/En)2~(0.1eV/GeV)2=10–20!
• Inteferometry (i.e., Michaelson-Morley)
– Need coherent source
– Need interference (i.e., large mixing angles)
– Need long baseline
Nature was kind to provide all of them!
• “neutrino interferometry” (a.k.a. neutrino oscillation) a unique tool to
study physics at very high scales
• Not entirely surprising (in retrospect) that neutrino mass was the first
evidence for physics beyond standard model
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Ubiquitous Neutrinos
They must have played some
important role in the universe!
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Astrophysical Probe
• Neutrinos unhindered by the entire star,
dusts, CMB, galactic & intergalactic B,
even last rescattering surface
• Possible probe into
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Core of stars (Sun, supernovae, GRB)
Near blackholes (AGN)
Dark Matter (Sun, galactic center, subhalo)
Cosmology?
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Present
Era of Revolution
The Data
Evidence for oscillation:
• “Indisputable”
– Atmospheric
– Solar
– Reactor
• “strong”
– Accelerator (K2K)
And we shouldn’t forget:
• “unconfirmed” excluded?
– Accelerator (LSND)
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SuperKamiokande
Atmospheric n disappear
2/dof=839.7/755 (18%)
m2=2.510-3 eV2
sin22=1
Downwards n’s don’t disappear
1/2 of upwards
n’s NNN
do 2007
disappear
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SNO
Solar n transform in flavor
2/3 of ne’s
 n
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KamLAND
Reactor neutrinos do oscillate!
TAUP 2007, preliminary
Proper time 
L0=180 km
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What we learned
• Lepton Flavor is not conserved
• Neutrinos have tiny mass, not very hierarchical
• Neutrinos mix a lot
the first evidence for
demise of the Minimal Standard Model
Very different from quarks
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The Big Questions
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What is the origin of neutrino mass?
Did neutrinos play a role in our existence?
Did neutrinos play a role in forming galaxies?
Did neutrinos play a role in birth of the universe?
Are neutrinos telling us something about
unification of matter and/or forces?
• Will neutrinos give us more surprises?
Big questions  tough questions to answer
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Immediate Questions
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Dirac or Majorana?
Absolute mass scale?
How small is 13?
CP Violation?
Mass hierarchy?
Is 23 maximal?
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Future
Bright Prospect
Immediate Questions
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Dirac or Majorana?
Absolute mass scale?
How small is 13?
CP Violation?
Mass hierarchy?
Is 23 maximal?
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Extended Standard Model
• Massive Neutrinos  Minimal SM incomplete
• How exactly do we extend it?
• Abandon either
– Minimality: introduce new unobserved light degrees
of freedom (right-handed neutrinos)
– Lepton number: abandon distinction between
neutrinos and anti-neutrinos and hence matter and
anti-matter
• Dirac or Majorana neutrino
• Without knowing which, we don’t know how to
extend the Standard Model
• KATRIN, 0n, Large Scale Structure
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Immediate Questions
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Dirac or Majorana?
Absolute mass scale?
How small is 13?
CP Violation?
Mass hierarchy?
Is 23 maximal?
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T2K (Tokai to Kamioka)
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Immediate Questions
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Dirac or Majorana?
Absolute mass scale?
How small is 13?
CP Violation?
Mass hierarchy?
Is 23 maximal?
LSND? Sterile neutrino(s)? CPT violation?
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LMA confirmed by KamLAND
• Dream case for neutrino oscillation physics!
• m2solar within reach of long-baseline expts
• Even CP violation may be probable
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P(n   n e )  P(n   n e )  16s12 c12 s13c13
s23c23
• Possible only if:
m 2
sin  sin 12
 4E
 m 2
L sin 13
  4E
 m 2
L sin 23
  4E

L 

– m122, s12 large enough (LMA)
– 13 large enough

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13 decides the future
• The value of 13 crucial for the future of neutrino
oscillation physics
• Determines the required
facility/parameters/baseline/energy
– sin2213>0.01  conventional neutrino beam
– sin2213<0.01   storage ring,  beam
• Two paths to determine 13
– Long-baseline accelerator: T2K, NOnA
– Reactor neutrino experiment: 2CHOOZ, Daya Bay
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NOnA
Fermilab to Minnesota
NOnA
25kt
MINOS
L=810km
32-plane
block
Admirer
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Daya Bay
Far site
1600 m from Ling Ao
2000 m from Daya
Overburden: 350 m
Empty detectors: moved to underground
halls through access tunnel.
Filled detectors: swapped between
underground halls via horizontal tunnels.
Ling Ao Near
500 m from Ling Ao
Overburden: 98 m
Mid site
~1000 m from Daya
Overburden: 208 m
Ling Ao-ll NPP
(under const.)
230 m
290 m
Entrance
portal
Ling Ao
NPP
Daya Bay Near
360 m from Daya Bay
Overburden: 97 m
Daya Bay
NPP
Total tunnel length: ~2700 m
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3 sensitivity on sin2 213
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T2K vs NOnA
• LBL nne
appearance
• Combination of
– sin2213
– Matter effect
– CP phase 
95%CL resolution
of mass hierarchy
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Accelerator vs Reactor
Reactor w 100t (3 yrs)
+T2K
T2K (5yr,n-only)
90%
CLyrs)
Reactor w
10t (3
+T2K
90% CL
Reactor experiments can help in
Resolving the 23 degeneracy
(Example: sin2223 = 0.95 ± 0.01)
Reactor w 100t (3 yrs) + Nova
Nova only (3yr + 3yr)
Reactor w 10t (3yrs) + Nova
90% CL
McConnel & Shaevitz, hep-ex/0409028
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My prejudice
• Let’s not write a
complicated theory
• The only natural measure
for mixing angles is the
group-theoretical invariant
Haar measure
• Kolmogorov–Smirnov
test: 64%
• sin2 213>0.04 (2)
• sin2 213>0.01 (99%CL)
13
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23
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T2KK
CP-violation may be observed
in neutrino oscillation!
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Big Questions
Need Synergies
Immediate Questions
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Dirac or Majorana?
Absolute mass scale?
How small is 13?
CP Violation?
Mass hierarchy?
Is 23 maximal?
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What about the Big Questions?
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What is the origin of neutrino mass?
Did neutrinos play a role in our existence?
Did neutrinos play a role in forming galaxies?
Did neutrinos play a role in birth of the universe?
Are neutrinos telling us something about
unification of matter and/or forces?
• Will neutrinos give us more surprises?
Big questions  tough questions to answer
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Seesaw Mechanism
• Why is neutrino mass so small?
• Need right-handed neutrinos to generate
neutrino mass , but nR SM neutral
n L

n R 
mD
mD n L 
2
m
  mn  D  mD
M n R 
M
To obtain m3~(m2atm)1/2, mD~mt, M3~1014–1015 GeV
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Leptogenesis
• You generate Lepton Asymmetry first. (Fukugita, Yanagida)
• Generate L from the direct CP violation in right-handed
neutrino decay
* *
(N1  n i H)  (N1  n i H)  Im(h1j h1k hlk hlj )
• L gets converted to B via EW anomaly
 More matter than anti-matter
 We have survived “The Great Annihilation”
• Despite detailed information on neutrino masses, it still
works (e.g., Bari, Buchmüller, Plümacher)
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Origin of Universe
V()
QuickTime™ and a
• Maybe an even bigger role
• Microscopically small Universe at
Big Bang got stretched by an
exponential expansion (inflation)
• Need a spinless field that
Cinepak decompressor
QuickTime™
andpicture.
a
are needed
to see this
Cinepak decompressor
are needed to see this picture.
– slowly rolls down the potential
– oscillates around it minimum
– decays to produce a thermal bath
(HM, Suzuki, Yanagida, Yokoyama)
log R
• The superpartner of right-handed
neutrino fits the bill
• When it decays, it produces the
lepton asymmetry at the same time

Neutrino is mother of the Universe?
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t
LHC/ILC may help
• LHC finds SUSY
• ILC measures masses precisely
• If both gaugino and sfermion
masses unify, there can’t be
new particles < 1014GeV except
for gauge-singlets
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Plausible scenario
• Lepton flavor violation
• 0n found
limits (e, e
• LHC discovers SUSY
conversion,  etc)
• ILC shows unification of
improve or discovered
gaugino and scalar masses
• Tevatron and EDM (e and
• Dark matter concordance
n) exclude Electroweak
between collider,
Baryogenesis
cosmology, direct
• CMB B-mode polarization
detection
gives tensor mode r=0.16
• CP in n-oscillation found
If this happens, we will be led to believe
seesaw+leptogenesis (Buckley, HM)
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Neutrinos as Astrophysical Probe
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Dark Matter
• Indirect detection of galactic dark matter
• From the Sun, Galactic Center, Subhalos
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ns & s
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EGRET down to =210-8cm-2sec-1
GLAST down to ~10-11cm-2sec-1
Neutrinos/km3: n~410-10cm-2sec-1
The catch:
QuickT imeý Dz
T IFFÅià•
èkǻǵŠj êLí£ÉvÉçÉO ÉâÉÄ
Ç™Ç±Ç ÃÉsÉNÉ `É ÉǾå©ÇÈÇ žÇ ½Ç …Ç ÕïKóvÇ­Ç•
ÅB
– GLAST>GeV
– Icecube>100GeV?
• Cross-correlation between ns & s gives us
understanding of the source
Buckley, Freese, HM, Spolyar, Sourav
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Dark Energy with Neutrinos?
• Supernova relic neutrinos
• In principle, sensitive to
come from cosmological
Dark Energy
distances
• HyperGADZOOKS!
SCDM
CDM
• Its spectrum redshifted
and superimposed
• Depends not only
supernova rates and
spectra, but also on the
4 Mt years
geometry of space
• Count Type-II@SNAP
Hall, HM, Papucci, Perez
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Conclusions
• Neutrino oscillation a unique tool to probe (very)
high-energy world
• Era of revolution
• sin2 213 decides the future of LBL expts
• My prejudice: 13 is “large”
• Reactor & accelerator LBL expts complementary
• To understand “big questions” we need a diverse
set of experiments
• Neutrinos are also unique astrophysical probes
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