Neutrino Masses and Mixings

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Neutrino Masses and Mixings Experiments Past,
Present, and Future
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ICHEP
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For three neutrinos
? masses
and mixings
Dave Wark
University of Sussex/RAL
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ICHEP
02
For three neutrinos
? masses
Three Angles
and mixings
Dave Wark
University of Sussex/RAL
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ICHEP
02
For three neutrinos
? masses
- each has a sign
and mixings
Dave Wark
University of Sussex/RAL
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Matter Effects the MSW effect
In vacuum
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Matter Effects the MSW effect
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Matter Effects the MSW effect
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Matter Effects the MSW effect
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ICHEP
02
For three neutrinos
? masses
- each has a sign
and mixings
Dave Wark
University of Sussex/RAL
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ICHEP
02
For three neutrinos
? masses
and mixings
Dave Wark
University of Sussex/RAL
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So what do we have to measure?

• Three Angles
• Two mass differences
• Two signs of the mass differences
• One CP phase
• But Also
• The absolute mass scale
• Are neutrinos Dirac or Majorana (or both)?
• Are there more - sterile - neutrinos
  (neuterinos)?

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So what do we have to measure?

• Most Importantly
• Is this the right model ?!?
• Many others have been proposed
• FCNC, extra dimensions, violations of the EP,
  neutrino decay, neutrino magnetic moments, etc.
• Must find signatures of oscillations
• Appearance of the wrong-flavour neutrinos
• Oscillation pattern
• Day/night or other matter effects

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Solar Neutrinos
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ICHEP
02
? masses
and mixings
Dave Wark
University of Sussex/RAL
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ICHEP
02
? masses
and mixings
Dave Wark
University of Sussex/RAL
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22,400 solar neutrino events!
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22,400 solar neutrino events!
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Super-Kamiokande Energy Spectrum
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Super-Kamiokande seasonal variation
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Day-night variation
Super Kamiokande
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Energy Scale
Calibrations
Efficiency
Reconstruction
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SNO Backgrounds
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The energy spectrum?
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So subtract these backgrounds ?
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Do they come from the sun?
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What does SuperK see?
16,700 electron type
5,700 mu or tau type!
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How will we learn more?

• From SNO
• Currently running with NaCl in the D2O
• Shortly to install discrete neutron counters
• Stringent test of NC systematics
• From others
• Long term too many to discuss here
• Short term
• KamLAND
• BOREXINO

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KamLAND
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KamLAND is taking data!
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Backgrounds are low!
First Results at PANIC?!?
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Borexino Physics Target 7Be neutrinos
Fill to start November 2002, data spring 2003
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SK can distinguish muons from electrons with
impressive precision
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SK data as a function of zenith angle
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Excellent fit to nm?nt
Very poor fit to nm?ne
Also results from Soudan II, MACRO
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t-appearance in Super-K
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Consequences for Q13
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From Nakayas talk at n02
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The first LBL Experiment K2K
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This conference saw a detailed presentation of
systematics
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K2Ks statement of the significance
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The MINOS Experiment
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1st Supermodule (1/2 detector) done, other well
begun
Meanwhile first magnetized data on atmospheric n
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Beam construction is well advanced, first beams
in 2006
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OPERA Detector Emulsion
2 kTon (Pb) 0.04 kTon emulsion
56 emulsion films / brick
9 kt-yr

• Dm2 1.2 x 10-3 eV2 2.7 events
• Dm2 2.4 x 10-3 eV2 11 events
• Dm2 5.4 x 10-3 eV2 54 events

• To the full detector
• 2 supermodules
• 31 walls / supermodule
• 52 x 64 bricks /wall
• 200 000 bricks

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3 kt to be in LNGS by 2005
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Dashed lines MINOS Ph2le, Ph2me, Ph2he from
right (A.Para, hep-ph/0005012)
A European proto-collaboration is organizing,
interested parties should contact me
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• Off-Axis (0.5-10) NuMI beam to surface detector
• sites in Minnesota (700 km) Canada (900 km)
  possible
• 20 kTon detector, possibly H20, possibly RPC,
  possibly scint.
• Sensitivity to q13 at 1.5 x 10-3 level
• LOI (Fermilab P929)
• http//www-numi.fnal.gov/fnal_minos/new_initiative
  s/
• Note 1-Day meeting at UC London, Monday
  September 16

And beyond these lies the Neutrino Factory.
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MiniBooNE
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First beam in August 02
First results?
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Determining the absolute mass scale

• Kinematic limits If you believe the oscillation
  results, all ?m21 eV, therefore only ne
  measurements have useful sensitivity -gt current
  best is Tritium Beta Decay
• If neutrinos have Marjorana masses, then
  zero-neutrino double-beta decay is allowed -gt
  observation of 0vBB decay would be direct
  evidence for neutrino mass
• Neutrinos are the second most numerous particle
  in the Universe -gt even a tiny neutrino mass
  could have cosmological implications
• All these have been used to set limits on
  neutrino mass

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Model Independent!
State-of-the-art experiments in Mainz and INR
(Troitsk)
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How to reach sub-eV sensitivity?
Make em bigger! -gt KATRIN
Troitsk Anomaly?
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Neutrinoless BB-decay limits
From Elliot and Vogel, hep-ph/0202264
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hep-ph/0201231
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Normal hierarchy
Inverted hierarchy
From Pascoli and Petcov, hep-ph/0205022
Need new experiments on much larger scale
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NEMO-3
100Mo at 1025 years
2.7m
Many many more, see Elliott and
Vogel hep-ph/0202264
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Cosmological studies of neutrino mass

• There are many cosmological consequences of
  neutrino mass too many to discuss here
• Specifically, however, neutrino mass will tend to
  wash out intermediate scale structure during
  galaxy formation
• This has recently been studied by the 2dF Galaxy
  Redshift Survey team (see astro-ph/0204152)

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They derive mn,tot lt 2.2 eV
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• There is no time (and I havent really got the
  expertise) to discuss this in detail here.
• I think it is tremendously exciting that
  cosmology and laboratory measurements are on the
  same scale, and therefore the information flows
  both ways.
• The cosmological measurements will push to
  greater sensitivity, down towards 0.1 eV.
• In my opinion such measurements are no substitute
  for good laboratory measurements, because they
  are inherently dependent on cosmological models
  we should be trying to test.
• For instance, there is the bias b, and if this
  is higher on small scales the 2dF analysis would
  derive a non-zero mass
• Laboratory limits therefore are potentially
  measures of b, which is very hard to measure
  otherwise!

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Conclusions!

• Neutrino mixing has moved from a speculation to
  an observed property of nature.
• For the simplest model we have measured 2 of the
  3 angles, 3 of the 2 mass differences, and the
  sign of one mass difference.
• Results over the next few years will be of great
  interest, with SNO, KamLAND, MiniBooNE, K2K,
  BOREXINO, MINOS, CNGS, and others all
  contributing new data
• The farther future leads from Superbeams through
  the Neutrino Factory, and we can look forward to
  new discoveries at each step
• Direct mass measurements, including double-beta
  decay, must be a priority
• There is much work to be done JOIN US!
• Thanks to everybody who I stole transparencies
  from!

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Signal PDFs for pure D2O
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CHOOZ / Palo Verde
Search for disappearance of reactor ne
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Make intense, energetic, clean, sign-selected
neutrino beams from m- ? e - nm ne
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