Neutrino Physics

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Neutrino Physics

• Caren Hagner
• Universität Hamburg

Part 3 Absolute neutrino mass
Introduction beta decay double beta
decay
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Nature of Neutrino Mass I
Neutrino fields v(x) with mass m are described by
the Dirac equation
From Goldhaber experiment one knows that vL is
realized.With m0 there is no need to have vR.
Therefore there were no vR in the Standard Model.
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Dirac Mass Term
The neutrino mass term in L could have exactly
the same formas the mass term of the quarks and
charged leptons
Dirac mass term
Lepton number is conserved!
Must add vR (right handed SU(2) singlets) to
standard model!
Problem When the mechanism is the same,
why are the masses so small?
mt 174.3 5.1 GeV mb (4.0-4.5) GeVmt
1776.99 0.29 MeV m3 lt 2eV
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Majorana Particles
Because neutrinos carry no electric charge(and
no color charge), there is the possibility
particle anti-particle
Majorana particle
But what about experiments?
There are two different states per flavorbut the
difference could be due to left-handed and
right-handed states!
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Majorana Mass Term
is a left-handed field
Note that
is a right-handed field
and
ok!
Lets try
Lepton number violation!
works too!
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Dirac-Majorana Mass Term
mass term for each flavor
mass matrix M
In order to obtain the mass eigenstates one must
diagonalize M
find unitary U with
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What if
1. mL mR 0 pure Dirac case
? 45, m1m2mD.
2 degenerate Majorana
states can be
combined to form 1 Dirac state.
2. mD 0 pure Majorana case
? 0, m1mL m2mR
per neutrino flavor one very light Majorana
neutrino v1L vL
one very heavy Majorana neutrino v2L (vR)c
mD of the order of lepton masses, mR reflects
scale of new physics? explains small neutrino
masses!
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Lower Limit of Neutrino Mass
Super-K (atmospheric neutrinos) ?m2atm 2.5
10-3 eV2 ? m(?i) 0.05 eV
This sets the energy scalefor mass search!
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Which mass hierarchy?

• Lightest neutrino mass not known
• ?m2atm lt 0 or gt0 ?

v3
?matm
0.05 eV
v2
?msolar
v1
?
0
normal hierarchy
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Tritium ß-Decay Mainz/Troitsk
E0 18.6 keV
dN/dE K F(E,Z) p Etot (E0-Ee)
(E0-Ee)2 mn2 1/2
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principle of an electrostatic filter
with magnetic adiabatic collimation (MAC-E)
adiabatic magnetic guiding of bs along field
lines in stray B-field of s.c. solenoids Bmax
6 T Bmin 310-4 T energy analysis by static
retarding E-field with varying strength high
pass filter with integral b transmission for EgtqU
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Results from the MAINZ Experiment
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The KArlsruhe TRItium Neutrino Experiment
KATRIN
70 m beamline, 40 s.c. solenoids
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Double-beta decay
Lepton number violation ?L 2
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Neutrinoless Double Beta Decay
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0v Doppel-Beta Experimente Ergebnisse
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Jedoch ein Teil der HdM Kollaboration
veröffentlicht Evidenz für 0v
Doppel-Beta Zerfall!
?
(Q 2039 keV für 76Ge Doppel-Beta Zerfall)
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Zukunft Heidelberg Ge Initiative (MPIK
Heidelberg)
Phase I 20kg angereichertes (86) 76Ge, vgl.
HDMPhase II 100 kgJahre, 0.1 0.3 eVPhase
III O(1t) angereichertes 76Ge, 10meV
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• CUORICINO _at_ Gran Sasso (Start 2003)

2v Doppelbeta mit 130Te (Q2529 keV) 18 crystals
3x3x6 cm3 44 crystals 5x5x5 cm340.7 kg of
TeO2 Suche nach 0v DoppelbetaT 1/2 0v (130Te) gt
7.5 x 1023 y ltmvgt lt 0.3 - 1. 6 eV
11 modules, 4 detector each, crystal dimension
5x5x5 cm3 crystal mass 790 g 4 x 11 x 0.79
34.76 kg of TeO2
2 modules, 9 detector each, crystal dimension
3x3x6 cm3 crystal mass 330 g 9 x 2 x 0.33 5.94
kg of TeO2
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End part 3
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Boris Kayser(at v2002)
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(No Transcript)
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Eigenstates of the interaction vL and vR
Mass eigenstates F1 (mass mL), F2 (mass mR)