Neutrino properties and oscillation experiments

1
Neutrino properties and oscillation experiments

• Alexander Friedland
• Los Alamos National Lab
• With C. Lunardini (INT, Seattle),
• M. Maltoni (SUNY, Stony Brook -gt ICTP),
• C. Peña-Garay (IAS)

2
A long-long time ago

• some people were suspecting that neutrinos could
  have unusual properties
• ?s could be massive and oscillate
• Pontecorvo (1957) Gribov Pontecorvo (1969),
• ?s could have non-standard interaction with
  matter
• Wolfenstein (1978)
• ?s could have magnetic moments and precess in
  the solar magnetic fields
• Cisneros (1971) Okun, Voloshin Vysotsky (1986)

3

• Then humans learned some more about neutrinos
• (state of things circa 2000)

4

• and more!

5
Now that we know so much

• What can we say about neutrinos?
• They do have masses, they mix, they oscillate ?
• Do they have non-standard interactions?
• Some bounds, much better bounds possible in near
  future
• Do they have magnetic moments?
• Some improvement possible in future
• Anything else? (Majorana/Dirac, sterile states,
  etc, etc, not in this talk)
• By measuring the matter effect we may be probing
  new physics above the EW scale

6
Digression philosophy

• Light scalars are in general unnatural in QFT.
• All the particles observed so far are fermions or
  gauge bosons (good!)
• But, a scalar (the Higgs) lies just around the
  corner
• New physics at the TeV scale?
• Search for this new physics
• write down effective operators suppressed by the
  new scale
• Search for their effects with precision low
  energy measurements
• A lot of effort in the quark and charge lepton
  sector (e.g., precision EW tests, exotic FV
  decays, proton decay)
• What can be done with neutrinos?

7
Some neutrino interactions are very poorly known

• Parameterize additional contributions due to
  heavy scalar/vector exchange as
• Well established only for the m-neutrino
• poorly known for the e-neutrino and especially
  the ?-neutrino (not using SU(2))

S. Davidson et al, JHEP 0303, 011 (2003)
8
Standard LMA solution physics

• 8B survival probability 30, flat (SNO,
  Super-K)
• GALLIUM experiments (SAGE, GALLEX GNO) see
  about 54 of the SSM prediction

• ?m2 is chosen to match the density in the solar
  core, such that the high-E ?s undergo adiabatic
  conversion (Peesin2?), while the low-E ones
  dont (Pee1-sin22?/2)

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Standard LMA solution physics

• For smaller ?m2/E, will hit the resonance
  condition in the Earth
• -gt need to worry about the Earth regeneration
  effect

• Put SNO and SK energies in the narrow flat
  window between the Earth and the solar resonances

10
Solar analysis setup

• Take the matter term in the osc. Hamiltonian to
  have the form
• The solar problem reduces to a 2x2 ?e-?? system

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Flavor-preserving NSI effects on solar neutrino
energy spectrum

• Shift P(E) to higher or lower E
• Change D/N asymmetry

M.M. Guzzo, P.C. de Holanda, O.L.G. Peres,
PLB5911,2004 hep-ph/0403134
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Flavor-changing NSI effects on solar neutrino
energy spectrum

• Transition from vacuum regime (low E?) to
  matter dominated regime (high E?) deviates from
  the canonical MSW profile

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Flavor-changing NSI effects on solar neutrino
energy spectrum

• Survival probability at SNO could show more or
  less energy dependence, depending on the sign of
  the NSI!
• Low-energy bin critical!

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Effect of the NSI on the solar survival
probability and day/night asymmetry

• Effect depends on the sign of ?e?!
• ?11u?11d?12u?12d0
• ?11u?11d-0.008, ?12u?12d-0.06
• ?11u?11d-0.044, ?12u?12d0.14
• ?11u?11d-0.044, ?12u?12d-0.14.

15
NSI can even lead to a new solution LMA-0

• Choose a point that cancels the d/n effect
• ?eed ?eeu-0.025,
• ?e?d ?e?u0.11,
• ???d ???u0.08.

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with completely non-trivial and testable
properties
Solar neutrino experiments
KamLAND
A. F., C. Lunardini, C. Peña-Garay,
PLB594347,2004 hep-ph/0402266
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LMA0 physics

• The d/n effect is proportional to sin(2?-2?),
  where ? is the vacuum angle and ? is the mixing
  in Hmat.
• When the d/n effect is suppressed, the allowed
  solar region extends to low ?m2

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Atmospheric neutrinos and NSI

• It was thought that such large NSI are excluded
  by the atmospheric ? data but that was based on a
  2-family ???? analysis
• The atmospheric analysis DOES NOT reduce to a 2x2
  ??-?? system!
• 3-family analysis finds that large NSI
  (?e????1) can be consistent with the data

A. F., C. Lunardini, M. Maltoni, PRD
70111301,2004 hep-ph/0408264 A. F., C.
Lunardini, PRD 72053009,2005 hep-ph/0506143
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Allowed NSI range fit and predictions
Scanned 4-D space (?e?, ???, ?m2,
?) marginalized over ?m2, ?
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Effect of NSI on the oscillation fit

• The best-fit region shifts to smaller ? and
  larger ?m2

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Testing the NSI

• Look for the upturn in Pee (SNO, Borexino?)
• 7Be line (Borexino, KamLAND?), to see if the flux
  is lower, as predicted by LMA-0
• Pep neutrinos!
• Atmospheric mixing angle should be probed by
  MINOS will test the large NSI possibility
• NO-LOSE situation confirmation of the standard
  scenario would place strong bounds on the NSI. In
  the opposite case, new physics at the 102-103 GeV!

22
Neutrino magnetic moment basics

• Dimension 5 operator
• Majorana neutrino spin precession (?! anti-?)
  must come with flavor change (e.g. ?e! anti-??)
• Flavor oscillations anti-?? ! anti-?e
• KamLAND is VERY sensitive to anti-?e from the Sun
  
• no reactor antineutrinos above 8.3 MeV
  conversions of solar 8B neutrinos -gt excess over
  predicted background
• Current bound . 3 10-4 ?e ! anti-?e conversion
  (KamLAND Phys. Rev. Lett. 92, 071301 (2004))

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Neutrino magnetic moment basics

• Generated in the Standard Model
• Because the SM is left-handed, highly suppressed
• Extensions of the SM could easily have larger
  contributions
• E.g, in left-right symmetric models

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Neutrino magnetic moment bounds

• Direct bounds ? lt 1 10-10 ?B (NUMU experiment,
  Phys. Lett. B564, 190, 2003)
• BBN bound wrong helicity ? production (Dirac
  only) ? . 5 10-10 ?B (FukugidaYazaki,
  PRD36,3817,1987)
• SK spect. distort. ? lt 1.5 10-10 ?B
  (BeacomVogel, PRL83,5222,1999)
• CMB Searches for spectral distortion caused by ?
  decay ? . 0.3 10-10 ?B (eV/m?)2.3
  (ResselTurner)
• Astrophysics red giant cooling, ? . 3 10-12 ?B
  (G. Raffelt, PRL64, 2856, 1990)

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If in the Sun, where?

• Two places with very different physics
• convective zone (r gt 0.7 RSUN)
• radiative zone (r lt 0.7 RSUN)

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Radiative Zone fields basics

• possible primordial fields
• Ohmic decay time 1010 years (Cowling, MNRAS,
  1945)
• Eight toroidal eigenmodes with lifetimes greater
  than the solar age, 4.6 Gyrs (A.F., A. Gruzinov,
  Astrophys. J. 601, 570, 2004)
• Strength constrained to be . a few MG (A.F., A.
  Gruzinov, Astrophys. J. 601, 570, 2004)
• Solar oblateness
• Stability of field configurations
  (double-diffusive instability)
• Helioseismology

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Lesson I need not worry about the Radiative
zone, even for ?? 10-11 ?B
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Convective Zone, Model I Uniform Kolmogorov
turbulence

• Assume magnetic field scales in a way typical for
  turbulent systems
• Estimate the field on the largest scales (0.1 R)
  of the turbulence from equipartition
• The effect comes out too small!

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Convective Zone, Model II Isolated flux tubes

• Plausible that the field in the CZ has a
  fibril'' nature, i.e., it is expelled by the
  turbulence and combines in isolated flux tubes.
  It was argued (E. Parker, 1984) that the total
  energy of the CZ (thermal gravitational
  magnetic) is reduced by the fibril state by
  avoiding the magnetic inhibition of convection
• Sunspot flux 1020 Mx, assume 100 kG fields ! 300
  km, close to optimal (neutrino oscillation
  length)!
• Comparing with total flux through the CZ, 1024
  Mx, neutrino encounters only several tubes

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Summary on magnetic moment

• Given the measured large value of the solar
  neutrino mixing angle, possible magnetic fields
  in the solar radiative interior cannot affect
  neutrino evolution
• Bounds based on the CZ spin-flip are greatly
  exaggerated did not treat magnetic field
  correctly
• Makes sense that KamLAND has not seen any
  antineutrinos from the Sun. May be on the edge of
  probing the optimistic scenario.