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Program

Program. The standard cosmological model The observed universe Inflation. Neutrinos in cosmology. The flatness problem (I). Rewrite Friedmann eq. as. Spatial flatness. The flatness problem (II). unstable. How our universe can be so flat today ?. The horizon problem. t_0. t_LS.

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Program

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  1. Program The standard cosmological model The observed universe Inflation. Neutrinos in cosmology

  2. The flatness problem (I) Rewrite Friedmann eq. as Spatial flatness

  3. The flatness problem (II) unstable How our universe can be so flat today ?

  4. The horizon problem t_0 t_LS Acausal volumes in our present Hubble volume How can be the CMB so uniform with no previous contact ?

  5. Inflation Period with Simplest example: (cosm. ct.) Solves flatness problem

  6. horizon physical scale Inflation expansion scale Solves homogeneity problem

  7. Inflation models Inflaton field evolving slowly in potential INFLATION Inflaton fluctuations produce perturbations Adiabatic (equal entropy per particle) Almost scale invariant (equal amplitude for all wavelengths)

  8. cosmology and neutrinos

  9. Impact of cosmology on neutrino properties • - Complementary to properties obtained • in solar/atmospheric/laboratory exps • is a “Cicerone” of the universe; • it plays or may play a role in almost all • epochs of the universe Big Bang Nucleosynthesis Cosmic Microwave Background Large Scale Structure …

  10. in the early universe Cicerone

  11. Expanding universe Luminosity distances Rate of expansion

  12. Weak interactions Neutrinos in thermal equilibrium Interaction rate Equilibrium when Number density Equilibrium distribution (No chemical potential)

  13. rates Neutrino decoupling after decoupling density dilutes and keep form because both (provided m<<T) (Exactly the reason why we observe photon black body today)

  14. Neutrino “temperature” From entropy cons. relic neutrino background (CNB) Properties of CNB can be obtained from CMB

  15. Big Bang Nucleosynthesis (BBN) Production of primordial nuclei - Helium mass-fraction - Deuterium and other light elements number-fraction … From PDG 2006

  16. Light element production depends on number neutrinos BBN Does not depend on mass provided (what it is important is the expansion rate) Parameterize deviations from In fact, (neutrino decoupling near e+e- annih.) N_eff takes into account other possible light fermions or bosons, even if not fully in thermal equilibrium with the rest

  17. Attitude has changed since baryon density is deduced from CMB observations BBN limits on neutrinos Tension between D and 4He, with 4He less in agreement with CMB Probably 4He systematics Limits on Neff are “author dependent” Evidence of cosmol. nus BBN may also probe non-standard interactions of neutrinos Review:Sarkar, hep-ph/9602260

  18. BBN NOT in crisis

  19. BBN and asymmetries Possibility not as constrained as for charged particles Introduce general distribution with chemical potentials 1.

  20. 2. BBN and asymmetries In principle, good bounds for nu_e and not as good for nu_mu and nu_tau BUT, take into account mixing/oscillations (Use density matrices to describe evolution) Tendency to flavor equilibrium

  21. Preferred solution Flavor evolution in BBN epoch Dolgov et al hep-ph/0201287 Serpico & Raffelt astro-ph/0506162 Updated bound Consequence: standard expectations on neutrino density OK

  22. in the late universe Cicerone

  23. Standard Cosmological Model

  24. Cosmological Observations CMB,LSS,SNIa Ly-alpha, lensing,…

  25. Standard Cosmological Model

  26. The bulk of the cosmological dark matter has to be cold. Neutrinos have to be subdominant. DM neutrinos OK with masses we have measured (excluding highly degenerate masses) cf. Structure formation lead by NR matter, impact of nus on structure formation? 1. move at v=c 2.

  27. Structure formation Graph from Raffelt

  28. Neutrino free-streaming suppreses growth of (small scale) structures Small scales affected Evolution equation at small scales (& other assumptions) (Notice ) Small f_nu, MD univ. Solution Expect change at scales smaller than horizon when nu become NR

  29. Power spectrum Lesgourgues, Pastor hep-astro/0603494

  30. Power spectrum From Strumia & Vissani hep-ph/0606054

  31. Neutrino mass and Cosmic Microwave Background Mass effect in CMB Massive nu goes from R to NR : *** R-M equality Change in expansion rate history Time variation of potentials in RD vs MD No big effects (not as large as LLS) but CMB important when doing a complete fit to all data

  32. Many authors using different inputs and different priors Neutrino-mass limits Fogli et al hep-ph/0608060 Absolute mass scale

  33. Neff limited by CMB+LSS+… N_effective of neutrinos (radiation) Change in expansion history Radiation smoothes small scale structure Hannestad astro-ph/0510582 CNB “detected” Generalization to thermal relics Hannestad & Raffelt astro-ph/0312154

  34. Most bounds in standard minimal Caveats in fact M=Mixed Care with degeneracies degeneracy m_nu and w broken by BAO Hannestad astro-ph/0505551 Minimal standard model (standard neutrinos) Experimental systematics (Remember 4He) Bias luminous/dark Bias-free limit Kristiansen et al astro-ph/0611761

  35. Future Lesgourgues, Pastor hep-astro/0603494

  36. Early universe, Late universe Neutrinos in the very early universe Sakharov conditions Problems of GUTS for baryogenesis Leptogenesis can generate B-asymmetry Decays of heavy Majoranas of see-saw. Relation to nu mass and mixing phases Neutrinos in the very late universe Scale of Dark Energy might be nu mass - Mass Varying Neutrinos - nu condensate

  37. Conclusion plays an active role in cosmology properties constrained by cosmology (complementary to other type of constraints)

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