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

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

3. The photon last scattering surface

4. Number density from thermodynamic equilibrium: Primordial Soup of Neutrinos, etc. 0.003 <   m < 0.15 Neutrino Dark Matter:

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

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

7. 3.43.23.0 BBNbaryometercalorimeter BBN: From a baryometer to a calorimeter The primordial He abundance: Y p = 0.238 ± 0.002 ± 0.005 (Olive, Steigman & Skillman 1997; Fields & Olive 1998) Y p = 0.244 ± 0.002 (Izotov & Thuan 1998)  Gives precision measurement of the energy density of the universe at ~ 1 sec!  Constrains new neutrino physics

8. BBN Allowed Orito et al ’02 astro-ph/0203352 CMB Allowed Using the observed abundances of D, 4 He, and 7 Li alone, BBN is very pliable to allow large neutrino asymmetries Due to cancelling effects between  and e, and baryon density,  b h 2 “Degenerate” Big Bang Nucleosynthesis

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

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

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

12. The Synchronized “Magnetic” Dipole of Neutrino Flavor

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

14. Atmospheric,  23 LMA Solar,  12  13

15. The cosmological neutrino density from  sol (Maltoni)

17. Non-zero:  13 > 10 -10   m 2 atm  m 2 sol 1 2 3 Normal Hierarchy Inverted Hierarchy   m 2 atm  m 2 sol 1 2 3

18. Light Sterile Neutrinos

19. 4-Neutrino Mass-modelling Maltoni, Schwetz, & Valle 2001, 2002; Päs, Song & Weiler 2002 “3+1”   m 2 atm  m 2 sol  m 2 LSND 1 2 3 4 “2+2”  m 2 sol   m 2 atm  m 2 LSND 4 3 1 2 

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

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

22. 3+1 Indirect  -> e Along with unitarity, forces large amplitude mixing with large  m 2, violating BBN bound “3+1”   m 2 atm  m 2 sol  m 2 LSND 1 2 3 4 K. Abazajian, Astropart. Phys., astro-ph/0205238

23. 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 “2+2”  m 2 sol   m 2 atm  m 2 LSND 4 3 1 2 K. Abazajian, Astropart. Phys., astro-ph/0205238

24. Assuming Standard Big Bang Nucleosynthesis Something more precise than “optimistic” and “pessimistic” limits And using only: 1.The Baryon Density: ● from the deuterium abundance: D/H = (3.0 ± 0.4) x 10 -5  b h 2 = 0.020 ± 0.002 (95% CL) (Burles, Nollet & Turner 2000; Burles & Tytler 1998) ● from the CMB:  b h 2 = 0.022(+0.004)(-0.003) (DASI+DMR) + (BOOMerANG) 2.The primordial helium abundance: Y p = 0.241± 0.002 ± 0.006 (Olive, Steigman & Skillman 1997; Fields & Olive 1998) (Izotov & Thuan 1998)

25. Constraint Evasion & New Physics 1.Pre-existing lepton number (L ~ 10 5 B) 2.A fifth mass eigenstate, mostly sterile may dynamically generate lepton number (Foot, Thomson & Volkas, 1996) sufficiently early 3.Generation of majoron fields (Berezinsky & Bento 2001) 4.Low reheating temperature (3 active neutrinos are not thermalized) 5.Baryon-Antibaryon inhomogeneities: N < 7 (Giovannini, Kurki- Suonio & Sihvola 2002) 6.Extended quintessence (“dark radiation”) (Chen, Scherrer & Steigman 2001) 7.CPT violating Neutrinos (Murayama & Yanagida 2001; Barenboim, Borrisov, Lykken & Smirnov 2001) 5

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

27. Summary… Future measurements of  LMA and  13 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