Hunting for Cosmological Neutrino Background (CvB)
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Transcript of Hunting for Cosmological Neutrino Background (CvB)
Hunting for Cosmological Neutrino Background
(CvB)Gianpiero Gianpiero Mangano Mangano
INFN, Sezione INFN, Sezione di Napoli, Italydi Napoli, Italy
NO-VE 2008
G. Mangano NO-VE 2008
CvB standard features
Neutrinos decoupled at T~MeV, keeping a “thermal” spectrum
Number density today
eV 94.1
mh Ω i
i2
ν
52 101.7h Ω ν
Energy density today
Tπ11
)3(ζ6n
113
)(p,Tfπ)2(pd
n 3CMB2γνν3
3
ν
massless
massive
G. Mangano NO-VE 2008
At T~me, e+e- pairs annihilate heating photons
γγ -ee
f=fFD(p,T)[1+δf(p)]
CvB details
… and neutrinos. Non thermal features in v distribution (small effect). Oscillations slightly modify the result
)(C,Em
G28
pM
Hpi 2W
F2
pt
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e
,
δf x10
1e
pp/T
2
10-2 effect
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nn
32
3
TT
)3(121
nnn
L
42
2715
Raffelt
Fermi-Dirac spectrum with temperature T and chemical potential =vTv
More radiation
CvB details
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/Tv very small (bad for detection!)
BBN, CMB (LSS) + oscillations
/Tv Hamann,
Lesgourgues and GM et al 08
/Tv
Cuoco et al 04
PLANCK
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CvB for optimists V produced by decays at some cosmological epoch
Early on: (TBBN> T>TCMB)
Late (T<< TCMB):
Unstable DM (e.g. Majoron) dm0
v H
1.0H0
Lattanzi and Valle ’07
Lattanzi et al (in progress)
Cuoco et al ‘05
Thermal FD spectrum
Distortion from Φ decay
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CvB indirect evidences
T < eVT ~ MeV
Formation of Large Scale Structures
LSS
Cosmic Microwave Background
CMB
PrimordialNucleosynthesis
BBN
Flavor blind flavor dependent
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Effect of neutrinos on BBN 1. Neff fixes the expansion rate during BBN
38ππ
H
2. Direct effect of electron neutrinos and antineutrinos on the n-p reactions
v
eff3/4
xvR N114
87
17Li
3He
D
4He
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Effect of CvB on CMB and LSSMean effect (Sachs-Wolfe, M-R equality)+ perturbations
Melchiorri and Trotta ‘04
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CvB locally: a closer look
Neutrinos cluster if massive (eV) on large cluster scale
Escape velocity: Milky Way 600 Km/s
clusters 103 Km/s
)eV/m(s/Km106m/Tcv v3
vvv
How to deal with: Boltzmann eq. + Poisson
2
vvxv
Ga4
0amf xf
Sing and Ma ’02
Ringwald and Wong ‘04
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Milky Way (1012 MO)
.
@ Earth
Ringwald and Wong ‘04
.
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Detection I: Stodolsky effect
Energy split of electron spin states in the v background
requires v chemical potential (Dirac) or net helicity (Majorana)
Requires breaking of isotropy (Earth velocity)
Results depend on D or M, relativistic/non relativistic, clustered/unclustered
Duda et al ‘01
)nn(sgGE vvAF
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The only well established linear effect in GFCoherent interaction of large De Broglie wavelength
Energy transfer at order GF2
)x(n(x) xdGF v3
F Cabibbo and Maiani ’82
Langacker et al ‘83
Torque on frozen magnetized macroscopic piece of material of dimension R
23
vv3
27 s cmcm 100nn
10Rcm
A100
10a
Presently Cavendish torsion balances
212 s cm10a
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Detection II: GF2
V-Nucleus collision: net momentum transfer due to Earth peculiar motion
2v
2FvN EG
v
vNA
vv
Ep
pAN
vna
v
v
Tp
mp
25446 s cm100A
)1010(a
Zeldovich and Khlopov ’81
Smith and Lewin ‘83
Coherence enhancesmm1/m - T/1 vvv
3v
Ac A
NN
Backgrounds: solar v + WIMPS
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Detection IIIAccelerator: vN scattering hopeless
Cosmic Rays (indirect): resonant v annihilation at mZ eV
meV
10 4m2
mE
v
21
v
2Z
Absorption dip (sensitive to high z)
Emission: Z burst above GZK (sensitive to GZK volume, (50 Mpc)3)
Ringwald ‘05
v capture (see later)
18 yr10R
LHC
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A ’62 paper by S. Weinberg and v chemical potential
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Massive neutrinos and neutrino capture on beta decaying nuclei
e 'NN v
v e 'NN
)1Z,A()Z,A(e
e)1Z,A()Z,A(
e
e
()
(A, Z) (A, Z 1)
Beta decay
e
e
()Neutrino Capture on aBeta Decaying Nucleus
(A, Z) (A, Z 1)
)(
)(
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dn/dEe
Qm
Ee-me
m 0
m= 0
2m
2 mv gap in electron spectrum around Q
Weinberg: if neutrinos are degenerate we could observe structures around the beta decaying nuclei endpoint Q
v’s are NOT degenerate but are massive!
Cocco et al ’07
see also Lazauskas et al ’07
Blennow ‘08
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Neutrino masses
Terrestrial bounds
ve <2 eV (3H decay)
v <0.19 MeV (pion decays)
v <18.2 MeV ( decays)
Cosmology Bounds on i mi
Courtesy of A.Marrone
G. Fogli et al. 2007
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Rates
Nuclear form factors (shape factors) uncertainties: use beta observables
Slow (neutral) particle capture
ee2
v
EpGR
v/R
vvvv Rnnv
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Background
Observing the last energy bins of width
signal/background >1
It works for <mv
dn/dTe
m Te
2m
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3H
1272 nuclei
799 nuclei
Beta decaying nuclei having BR() > 5 selected from 14543 decays listed in the ENSDF database
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The 3H example
8 events yr-1 per 100g of 3H (no clustering)
up to 102 events yr-1 per 100 g of 3H due to clustering effect
signal/background = 3 for =0.2 eV if mv=0.7 eV
=0.1 eV if mv=0.3 eV
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Variation on the theme:
Beta-beams
Electron-capture nuclei (fighting with energy threshold!)
Best nucleus candidate?
Already there ? (Troisk anomaly) Unlikely large flux!!
Waiting for Katrin
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Conclusions
vAP Collaboration CvB map
20??