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Hunting for Cosmological Neutrino Background (CvB)

NO-VE 2008. Hunting for Cosmological Neutrino Background (CvB). Gianpiero Mangano INFN, Sezione di Napoli, Italy. CvB standard features. Neutrinos decoupled at T~MeV, keeping a “thermal” spectrum. Number density today. Energy density today. massless. massive. CvB details.

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Hunting for Cosmological Neutrino Background (CvB)

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  1. NO-VE 2008 Hunting for Cosmological Neutrino Background (CvB) Gianpiero Mangano INFN, Sezione di Napoli, Italy

  2. CvB standard features Neutrinos decoupled at T~MeV, keeping a “thermal” spectrum Number density today Energy density today massless massive G. Mangano NO-VE 2008

  3. CvB details At T~me, e+e- pairs annihilate heating photons … and neutrinos. Non thermal features in v distribution (small effect). Oscillations slightly modify the result f=fFD(p,T)[1+δf(p)] G. Mangano NO-VE 2008

  4. e , δf x10 10-2 effect G. Mangano NO-VE 2008

  5. CvB details Fermi-Dirac spectrum with temperature T and chemical potential =vTv Raffelt More radiation G. Mangano NO-VE 2008

  6. /Tv very small (bad for detection!) BBN, CMB (LSS) + oscillations Cuoco et al 04 PLANCK /Tv /Tv Hamann, Lesgourgues and GM et al 08 G. Mangano NO-VE 2008

  7. CvB for optimists V produced by decays at some cosmological epoch Early on: (TBBN> T>TCMB) ThermalFD spectrum Distortion from Φdecay Cuoco et al ‘05 Late (T<< TCMB): Unstable DM (e.g. Majoron) Lattanzi and Valle ’07 Lattanzi et al (in progress) G. Mangano NO-VE 2008

  8. CvB indirect evidences Primordial Nucleosynthesis BBN Cosmic Microwave Background CMB Formation of Large Scale Structures LSS T ~ MeV T < eV flavor dependent Flavor blind G. Mangano NO-VE 2008

  9. Effect of neutrinos on BBN 1. Neff fixes the expansion rate during BBN D 3He 7Li 4He 2. Direct effect of electron neutrinos and antineutrinos on the n-p reactions G. Mangano NO-VE 2008

  10. Effect of CvB on CMB and LSS Mean effect (Sachs-Wolfe, M-R equality)+ perturbations Melchiorri and Trotta ‘04 G. Mangano NO-VE 2008

  11. 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 How to deal with: Boltzmann eq. + Poisson Sing and Ma ’02 Ringwald and Wong ‘04 G. Mangano NO-VE 2008

  12. . Milky Way (1012 MO) Ringwald and Wong ‘04 . @ Earth G. Mangano NO-VE 2008

  13. 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 G. Mangano NO-VE 2008

  14. Torque on frozen magnetized macroscopic piece of material of dimension R Presently Cavendish torsion balances The only well established linear effect in GF Coherent interaction of large De Broglie wavelength Energy transfer at order GF2 Cabibbo and Maiani ’82 Langacker et al ‘83 G. Mangano NO-VE 2008

  15. Detection II: GF2 V-Nucleus collision: net momentum transfer due to Earth peculiar motion Coherence enhances Zeldovich and Khlopov ’81 Smith and Lewin ‘83 Backgrounds: solar v + WIMPS G. Mangano NO-VE 2008

  16. Detection III Accelerator: vN scattering hopeless LHC v capture (see later) Cosmic Rays (indirect): resonant v annihilation at mZ Absorption dip (sensitive to high z) Emission: Z burst above GZK (sensitive to GZK volume, (50 Mpc)3) G. Mangano NO-VE 2008 Ringwald ‘05

  17. A ’62 paper by S. Weinberg and v chemical potential G. Mangano NO-VE 2008

  18. Massive neutrinos and neutrino capture on beta decaying nuclei e Beta decay () e (A, Z  1) (A, Z) Neutrino Capture on a Beta Decaying Nucleus e () e (A, Z  1) (A, Z) G. Mangano NO-VE 2008

  19. Weinberg: if neutrinos are degenerate we could observe structures around the beta decaying nuclei endpoint Q v’s are NOT degenerate but are massive! 2 mv gap in electron spectrum around Q dn/dEe m= 0 m 0 Q Ee-me m Cocco et al ’07 see also Lazauskas et al ’07 Blennow ‘08 2m G. Mangano NO-VE 2008

  20. Neutrino masses Bounds on i mi Courtesy of A.Marrone Terrestrial bounds ve <2 eV (3H decay) v <0.19 MeV (pion decays) v <18.2 MeV ( decays) Cosmology G. Mangano NO-VE 2008 G. Fogli et al. 2007

  21. Rates Slow (neutral) particle capture Nuclear form factors (shape factors) uncertainties: use beta observables G. Mangano NO-VE 2008

  22.    Background  dn/dTe Observing the last energy bins of width  Te m 2m signal/background >1 It works for <mv G. Mangano NO-VE 2008

  23. 3H 1272  nuclei 799  nuclei Beta decaying nuclei having BR() > 5  selected from 14543 decays listed in the ENSDF database G. Mangano NO-VE 2008

  24. 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 G. Mangano NO-VE 2008

  25. 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 G. Mangano NO-VE 2008

  26. Conclusions vAP Collaboration CvB map 20?? G. Mangano NO-VE 2008

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