Baryo-through-Leptogenesis and CP violation in neutrino oscillations

1. Baryo-through-Leptogenesisand CP violation in neutrino oscillations José Bernabéu U. de Valencia and IFIC MODERN COSMOLOGY INFLATION, CMB and LSS Centro de Ciencias de Benasque, August 2006

2. Baryo-through-Leptogenesis andCP violation in neutrino oscillations • Baryogenesis • Origin of neutrino mass • Leptogenesis • Experiments 1998  2006 • What is known, what is unknown • Second generation approved experiments for U(e3) and third generation proposals for the CP phase δ • Interest of energy dependence in suppressed neutrino oscillations

3. Baryo-through-Leptogenesis andCP violation in neutrino oscillations • Electron Capture: how to reach a superallowed transition and a short lifetime for the radioactive ion. • Gamow-Teller resonance in the final state  Definite neutrino energy. Rare-earth nuclei around 146Gd. • Electron Capture Facility for a monochromatic -beam • Electron neutrino flux in LAB frame • Physics reach for θ13and δ • Feasibility and prospects

4. Baryogenesis • Particle Physics has a SM, except for neutrino physics. Cosmology has a SCM. But SCM + SM incompatible without new physical phenomena. BARYOGENESIS is probably one phenomenon demanding new physics. • The charge asymmetry of the Universe needs a dynamical generation, given by the Sakharov conditions: 1) B- Violation, “natural” in GUT’s and in SM (with sphalerons); 2) C and CP- Violation, experimentally established; 3) Deviation from thermal equilibrium <--> First order phase transition. • One number to be explained: (n(B)-n(Bbar))/n(photons)= 6 x 10*(-10). • In principle, Baryogenesis is possible within the SM, but… 1) The EW phase transition (Higgs) cannot be first order; 2) CP- Violation induced by the CKM mixing matrix among quarks is short by more than 10*10 in Asymmetry. • A possible scenario is Baryo-through-Leptogenesis  NEW PHYSICS: NEW HEAVY MAJORANA PARTICLES, with L- violating interaction & mass terms, and NEW SOURCES OF CP-VIOLATION.

5. Origin of masses Why are Neutrino Masses so small? even for a smooth LOG – scale…

6. Origin of masses i) With νLonly, massive neutrinos have to be Majorana ii) A Majorana mass term can not be, however, generated by SSB in the SM. Take particle content of SM and ask: what is the lowest dimension non- renormalizable operator with SU(2) x U(1) gauge invariance? UNIQUE Dim. 5

7. Origin of masses • L = 2 • F mixing, LFV • After SSB of Leff: Leff →Lmass “see –saw” type Why so light? Maj Neutrino mass matrix Conclusion Lmassfor “light” neutrinos GENERATED from Leff (at present energies) and from L = 2 interactions at high energies Λ Maj • Origin of  ? • Heavy mass R ?: conventional “See-Saw” • Fierz-reordering: other models

8. The Pontecorvo MNS Matrix After diagonalization of the neutrino mass matrix,  For Flavour oscillations U: 3 mixings, 1 phase Even if they are Majorana • Atmospheric KEK More LBL-beams Appearance e! Reactor Matter in Atmospheric… • Solar KAMLAND

15. Experiments 1998 - 2006

16. Experiments 1998-2006 • Solar neutrinos • Homestake: 1/3 deficit for intermediate energy neutrinos and CC detection • Kamiokande and SuperKamiokande: ½ deficit for high energy neutrinos and elastic scattering detection • Gallium experiments: 0.6 deficit for low energy neutrinos and CC detection • SNOsolution: NC νx flux = 3 CC νe flux for high energy neutrinos + total flux compatible with astrophysical calculations  Solution in terms of neutrino oscillations in Sun matter for νe to an equal combination of νμand ντ • KamLAND confirmation for reactor νe in terms of vacuum oscillations for long baseline detection

17. Experiments 1998-2006 • Atmospheric neutrinos • Early deficit in the ratio N(νμ)/N(νe) • Zenith effect in SuperKamiokande: dependence for high energy νμneutrinos, non dependence for νe neutrinos + non deficit for short baseline neutrinos + increasing deficit for baselines above 6000 Km • Soudan II and MACRO confirmed the results with some information on the L/E dependence  Solution in terms of neutrino oscillations for νμto ντ • Confirmation from acceleratorνμK2K experiment: survival probability + energy dependence

19. Neutrino flavour oscillations What is known, what is unknown ? Absolute neutrino masses ? 3 H, Cosmology • Form of the mass spectrum • Matter effect in neutrino propagation Majorana neutrinos ?  0: masses and phases

20. First very recent results from MINOS From Fermilab to Sudan,  disappearance: L/E dependence Energy resolution in the detector allows a better sensitivity in Δm223 : compatible with previous results with some tendency to higher values

22. How many Δm2 ‘s ? • All interpretations on neutrino oscillations in terms of two Δm2 ‘s: atmospheric and solar, that is, three active neutrinos. • Los Alamos experiment would imply a new Δm2 of the order of (eV)2, i. e., at least one aditional sterile neutrino. • Near future results from MiniBoone should clarify the issue. • I will assume in the rest of the presentation three active neutrinos only.

23. Second generation approved experiments for U(e3) • Appearance experiments for the suppressed transition νμνe : T2K, NOVA Off-axis neutrino beam from Fermilab to Soudan From J-PARC to SK

24. Second generation approved experiments for U(e3) • Disappearance experiment from reactor νe: CHOOZ DoubleCHOOZ at short and intermediate baselines with near and far detectors. The most stringent constraint on the third mixing angle comes from the CHOOZ reactor neutrino experiment with sin2(2θ13)<0.2. DoubleChooz will explore the range of sin2(2θ13) from 0.2 to 0.03-0.02, within three years of data taking.

25. Interest of energy dependence in suppressed neutrino oscillations After atmospheric and solar discoveries and accelerator and reactor measurements → θ13 , δ CP violation accessible in suppressed appearance experiments Appearance probability: |Ue3| gives the strength of P(ne→νμ) δ acts as a phase shift

26. CONCLUSION • SM Baryogenesis seems inefficient. • Leptogenesis has all the good ingredients. It needs a Majorana fermion at high scales. • Any link to present neutrino physics? SEE-SAW connects m(L) with M(R). 4. Leptogenesis depends on CP-odd M(R). • Neutrino masses and mixings determined by m(L)  CP-Violating Neutrino Oscillations. • How to observe CP-phase? Phase-shift in suppressed e-neutrino  mu-neutrino transition.

27. Interest of energy dependence in suppressed neutrino oscillations CP violation: CPT invariance + CP violation = T non-invariance No Absorptive part  Hermitian Hamiltonian  CP odd = T odd = is an odd function of time = L ! In vacuum neutrino oscillations L/E dependence, so This suggest the idea of a monochromatic neutrino beam to separate δ and |Ue3| by energy dependence!

28. Z protons N neutrons Z-1 protons N+1 neutrons Neutrinos from electron capture How can we obtain a monochromatic neutrino beam? Electron capture: boost Forward direction 2 body decay! a single discrete energy if a single final nuclear level is populated From the single energy e--capture neutrino spectrum, we can get a pure and monochromatic beam by accelerating ec-unstable ions

29. An idea whose time has arrived ! • In heavy nuclei (rate proportional to square wave function at the origin) and proton rich nuclei (to restore the same orbital angular momentum for protons and neutrons ) •  Superallowed Gamow-Teller transition The “breakthrough” came thanks to the recent discovery of isotopes with half-lives of a few minutes or less, which decay mainly through electron capture to a single Gamow-Teller resonance.

30. Ion Candidates Ions must have a mean life short enough to allow them to decay in the storage ring before they lose its electron. The recent discovery of nuclei that decay fast enough through electron capture opens a window for real experiments.

31. Implementation The facility would require a different approach to acceleration and storage of the ion beam compared to the standard beta-beam, as the atomic electrons of the ions cannot be fully stripped. Partly charged ions have a short vacuum life-time. The isotopes we will discuss have to have a half-life ≤ vacuum half-life ~ few minutes. For the rest, setup similar to that of a beta-beam. Brief recall : Ions produced at EURISOL Accelerated by the SPS Stored in a storage ring, straight sections point to detector

32. Electron neutrino flux • Assuming no oscillation: - In the proper frame of the radiocative ion - In terms of LAB variables for energy EL and angle θL where J is the Jacobian - In the LAB, contrary to the proper frame, there is a correlation between EL and θL. For long baseline experiments, detected neutrinos are inside a narrow cone around θL = 0 , by adjusting the long straight section of the decaying ring.

33. Electron neutrino flux - For γ >>1 the neutrino flux in the forward direction is given by Branching ratio Flux: - Notice the proportionality with γ2 We want to have a proper neutrino energy E0 low enough so that a given E=2γE0 , estimated from the baseline L, implies a high ,and then higher neutrino flux.

34. Experimental Set-up • Number of muons produced in CC interactions in the detector at a fixed • baseline L Statistical Analysis by Calculating and fit to the value for the assumed parameters by minimizing х2 Cross Section per water molecule

35. Experimental set-up 5 years g =90 (close to minimum energy above threshold) 5 years g = 195 (maximum achievable at present SPS) Versus 10 years for each γ 1018 decaying ions/year 440 kton water ckov detector OR … appropriate changes If higher production rates Distance: 130 km (CERN-Frejus) Appearance & Disappearance

36. Results for appearance and disappearance

37. Disentangling θ13 and δ Much better separation for two different energies, even with lower statistics Access to measure the CP phase as a phase- shift

38. The virtues of two energies 130 km

39. Fit of 13 ,  from statistical distribution The principle of an energy dependent measurement is working and a window is open to the discovery of CP violation

40. Exclusion plot: sensitivity Total running time: 10 years... Impressive!! Significant even at 1o

41. Exclusion plot: δ≠0sensitivity Total running time: 10 years... Significant for θ13 > 40

42. Feasibility • Acceleration and storage of partly charged ions • Experience at GSI and the calculations for the decay ring yield less than 5% of stripping losses per minute • A Dy atom with only one 1s electron left would still yield more than 40% of the yield of the neutral Dy atom  with an isotope having an EC half-life of 1 minute, a source rate of 1013 ions per second, a rate of 1018’s per year along one of the straight sections could be achieved (M. Lindroos) - A new effort is on its way to re-visit the rare-earth region on the nuclear cart and measure the EC properties of possible candidates. The best: a half life of less than 1 min with an EC decay feeding one single nuclear level.

43. Physics Prospects • Most important is to determine the full physics reach for oscillation physics with a monochromatic neutrino beam: it would allow to concentrate the intensity in the most sensitive points in E/L to disentangle δ … By increasing the boosted neutrino energy and varying the baseline: Canfranc?, Frejus?, a combination of the two L’s? … By combining EC neutrinos with - antineutrinos from 6He … How to improve cross section results for  and e for water? Thanks to : C. Espinoza J. Burguet-Castell M. Lindroos

44. CONCLUSION • SM Baryogenesis seems inefficient. • Leptogenesis has all the good ingredients. It needs a Majorana fermion at high scales. • Any link to present neutrino physics? SEE-SAW connects m(L) with M(R). 4. Leptogenesis depends on CP-odd M(R). • Neutrino masses and mixings determined by m(L)  CP-Violating Neutrino Oscillations. • How to observe CP-phase? Phase-shift in suppressed e-neutrino  mu-neutrino transition.