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The Cosmological Energy Density of Neutrinos from Oscillation Measurements

The Cosmological Energy Density of Neutrinos from Oscillation Measurements. June 10, 2003. Kev Abazajian Fermilab. NuFact 03 – Fifth International Workshop on Neutrino Factories & Superbeams. WMAP: Measurement of 10 -5 fluctuations on the entire sky to ~0.25 °.

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The Cosmological Energy Density of Neutrinos from Oscillation Measurements

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  1. The Cosmological Energy Density of Neutrinos from Oscillation Measurements June 10, 2003 Kev Abazajian Fermilab NuFact 03 – Fifth International Workshop on Neutrino Factories & Superbeams

  2. WMAP: Measurement of 10-5fluctuations on the entire sky to ~0.25°

  3. The photon last scattering surface

  4. Neutrino Dark Matter: 0.003 < Wn/Wm < 0.15 Primordial Soup of Neutrinos, etc. Number density from thermodynamic equilibrium:

  5. WMAP ►Consistency with baryon density at 300,000 years later, at CMB decoupling Big Bang Nucleosynthesis ►concordance of light element abundances with standard theory

  6. Neutrino energy density beyond the standard model (assumption) • Neutrino Asymmetry: • Extra Neutrino Flavors: ns, ns’, ns’’ … Models: 2+2, 3+1, 3+2, 3+N …

  7. 3.4 3.2 3.0  Gives precision measurement of the energy density of the universe at ~ 1 sec!  Constrains new neutrino physics BBN: From a baryometer to a calorimeter The primordial He abundance: Yp = 0.238 ± 0.002 ± 0.005 (Olive, Steigman & Skillman 1997; Fields & Olive 1998) Yp = 0.244 ± 0.002 (Izotov & Thuan 1998)

  8. CMB CMB Allowed “Degenerate” Big Bang Nucleosynthesis Using the observed abundances of D, 4He, and 7Li alone, BBN is very pliable to allow large neutrino asymmetries Due to cancelling effects between nm/tand ne, and baryon density, Wbh2 BBN Allowed BBN Allowed Orito et al ’02 astro-ph/0203352

  9. Evolution of Neutrino Asymmetries in the Early Universe Thermal Potential (finite temperature effects) Vacuum Oscillation e+/- / m+/- background Neutrino Self-Potential

  10. Transformation of neutrino asymmetries number density of neutrinos Generally: LMA solar + maximal ATM Any chemical potential will alter the 4He abundance. x <<1 Dolgov et al. (Dolgov et al, hep-ph/0201287 ; Abazajian, Beacom, Bell astro-ph/0203442 ; Wong hep-ph/0203180 )

  11. Neutrino Flavor Momentum Synchronization… Abazajian, Beacom & Bell astro-ph/0203442

  12. The Synchronized “Magnetic” Dipole of Neutrino Flavor

  13. CMB Allowed: BBN + LMA+Atm Allowed The Death of Degenerate BBN and New Constraints… Allowed Allowed

  14. q13 LMASolar, q12 Atmospheric, q23

  15. The cosmological neutrino density from qsol (Maltoni)

  16. n3 n3 dm2atm dm2atm n2 n2 dm2sol dm2sol n1 n1 Non-zero: q13 > 10-10 Normal Hierarchy Inverted Hierarchy

  17. Light Sterile Neutrinos

  18. “2+2” “3+1” n4 n4 dm2atm n3 n3 dm2atm n2 n2 dm2sol dm2sol n1 n1 dm2LSND dm2LSND  4-Neutrino Mass-modelling Maltoni, Schwetz, & Valle 2001, 2002; Päs, Song & Weiler 2002

  19. Constraining Sterile Neutrino Mixing • Collisions decohere neutrino gas and populate sterile neutrinos • Requiring that ns are not equilibrated (Nn<4) The relevant amplitude is simply:

  20. Original 2-neutrino limits:Langacker 1989;Barbieri & Dolgov 1990;Enqvist, Kainulainen, Thomson 1992;Shi, Schramm & Fields 1993 Application to all 4 neutrino models:K. Abazajian, Astropart. Phys., astro-ph/0205238; P. Di Bari, PRD 65, 043509 (2002)

  21. “3+1” n4 n3 dm2atm n2 dm2sol n1 dm2LSND 3+1 Indirect nm -> ne Along with unitarity, forces large amplitude mixing with large dm2, violating BBN bound K. Abazajian, Astropart. Phys., astro-ph/0205238

  22. “2+2” n4 dm2atm n3 dm2LSND n2 dm2sol n1 2+2 Both solar (SNO) – neutral current signal of D breakup and capture and atmospheric (Super-K) – enhanced neutral current component and matter effects experiments are now effectively appearance experiments, and disfavor large sterile components Sterile must be split between upper and lower doublet K. Abazajian, Astropart. Phys., astro-ph/0205238

  23. Assuming Standard Big Bang Nucleosynthesis • Something more precise than “optimistic” and “pessimistic” limits • And using only: • The Baryon Density:● from the deuterium abundance:D/H = (3.0 ± 0.4) x 10-5Wbh2 = 0.020 ± 0.002 (95% CL)(Burles, Nollet & Turner 2000; Burles & Tytler 1998)● from the CMB:Wbh2 = 0.022(+0.004)(-0.003)(DASI+DMR) + (BOOMerANG) • The primordial helium abundance:Yp = 0.241± 0.002 ± 0.006 (Olive, Steigman & Skillman 1997; Fields & Olive 1998)(Izotov & Thuan 1998)

  24. Constraint Evasion & New Physics • Pre-existing lepton number (L ~ 105 B) • A fifth mass eigenstate, mostly sterilemay dynamically generate lepton number (Foot, Thomson & Volkas, 1996) sufficiently early • Generation of majoron fields (Berezinsky & Bento 2001) • Low reheating temperature (3 active neutrinos are not thermalized) • Baryon-Antibaryon inhomogeneities: Nn< 7 (Giovannini, Kurki-Suonio & Sihvola 2002) • Extended quintessence (“dark radiation”) (Chen, Scherrer & Steigman 2001) • CPT violating Neutrinos (Murayama & Yanagida 2001; Barenboim, Borrisov, Lykken & Smirnov 2001) n5

  25. The MiniBooNE Experiment … see Ion Stancu’s talk (next)

  26. Summary… • Future measurements of qLMA and q13 will further constrain the cosmological neutrino density • Big bang nucleosynthesis and the CMB (in the future) is • Best probe of relic neutrino asymmetries • And has consequences for four neutrino models, or vice-versa

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