ELECTROMAGNETIC INTERACTIONS OF NEUTRINOS IN MATTER

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ELECTROMAGNETIC INTERACTIONS OF NEUTRINOS IN
MATTER
Int. School of Nuclear Physics Probing hadron
structure with lepton hadron beams
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E.M. interactions of neutrinos

1. Radiative decays
2. Magnetic moment
3. Stimulated conversion all GIM suppressed in
   vacuum!

g
l
n2
n1
W
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Present limits
Radiative decays SM theory t0 7 1043
(1eV/m)5 (s) Pal Wolfenstein
(1982) Experiments SN1987 (strong MH)
t/m gt 6 1015 s/eV Bugey (mass
degenerated) t/m gt 310-4 s/eV if dm/m gt10-7
Solar eclipse t/m gt 100 s/eV if dm2 10-5
eV2
Magnetic moment SM theory mn 3.2 10-19
m(eV) mB Experiment (solar) m lt 0.54 10-10 mB
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Amplification in matter
J.C.dOlivo, J.F.Nieves (1989), G.Giunti et al.
(1991)
Coherent interactions on the atomic electrons
n2
g
e
W
n1
e
t0/tm 9 1023 F(v)(Ne/1024cm-3)2 (1eV/m)4 If
mass-degenerated t0/tm 9 1023
F(v)(Ne/1024cm-3)2 (1eV/m)4 (m2/dm2)2
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Neutrino energy deposition in a Ge crystal
Neutrino beam ?
High purity Ge diode 140 cm3 at liquid nitrogen
temperature (77K) Electron-hole pair creation
work 3 eV very low energy threshold Energy
resolution keV
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Integral search the principle
A.Castera et al., Phys.Lett.B452, 150
High intensity n beam 20 GeV 1013 pot in 4 ms
spills, every 14 s 1 mip (muon) gives a sudden
signal 30 MeV in 5 cm Search Continuous
energy deposition building up during the spill
duration
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Results
Clear on-beam signal of crossing mips
No excess of deposited energy lt 3 keV in 5 cm
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Analysis
8 107 nm and anti-nm per spill crossing the
crystal Total energy deposition lt 3 keV in 5 cm
of Ge lt 10-5 eV /cm 10-12 normal dE/dx lt 10
keV for whole earth diameter 10-2 eV /cm for
weak interactions Case of mass-degenerated
radiative decay Eg En dm2/m2 En 2dm/m 2
eV lt Eg lt 200 eV 10-10 lt dm/m lt 10-8 Prob lt
10-5/Eg tm gt 5/3 10-5 dm2/m t0 gt
1.5 1018 m3/dm2
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An encore at the Bugey reactor
Powerful source of anti-ne 1021/s But also ne
from activation of the container 55Fe produces a
peak at 230 keV and 51Cr peak at 750 keV 15 m
from the core 4 109 /cm2 for each of the 2 peaks
tm/m gt 3 10-4 s/eV in Ge equivalent to t0/m gt 9
1015 s/eV in vacuum
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Stimulated conversion in an RF cavity

• Another way to amplify EM interactions
• M.C Gonzalès-Garcia, F. Vannucci and J.
  Castromonte Phys.Lett. B373,153(1996)
• Idea an RF cavity is a photon bath (100W 109
  QF1023 g/cm3 à 10-6 eV)
• Majorana neutrinos nm ? anti-ne ou anti-nt
• Dirac neutrinos nm ? sterile n
• R DN/N (Q/109)(P/100W)(m/eV)3(eV2/dm2)3(s/t)
• t0 20/R (m/dm2)3
• If Rlt10-2 t0 gt 2 1018s for dm210-5 eV2 and
  m1 eV
• But also n 2 g ? g n 1

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Recent development sterile neutrinos
What are sterile neutrinos? -Do not participate
in Weak Interactions -Couple to the real world
through mixing (ne, nm, nt, nH ) U (n1,
n2, n3, n4 ) Bad reasons try to explain
anomalies in past neutrino data LSND, MiniBoone,
nuclear reactors, radioactive sources
Good reasons neutrinos are massive, need of
Right Handed components Classical see-saw model,
very high masses, but variations exist Every
neutrino flux has some nH component at the level
of UHl2
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Example the nMSM model
Three sterile neutrinos, one of them having 10
keV/c2 mass
t0 7 1043 (1eV/m)5(1/U2) (s)

• Almost stable ? DARK MATTER
• ? Warm Dark Matter

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Cosmological limits
Search of monoenergetic photons
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Sterile neutrinos as WDM
m(nH) 7 keV U2 10-10 In vacuum t0 4 1034
s In matter tm 1026 s
Local Dark Matter density 300 MeV/cm3 Relative
velocity 200 km/s Flux of nH on earth 8 1011
nH/cm2s (yearly modulation) In crystal 1x1x1 m3
10-8 decay/year !! 5 10-4/year in SK, 10/year
in IceCube
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Conclusion
EM neutrino interactions exist in the Standard
Model -Recent claim in astrophysics of radiative
decay indication? They are hugely amplified in
matter but not yet enough to consider an
experiment in the lab Unless nuclear physics
help?