Baryo-through-Leptogenesis
and CP violation in neutrino oscillations
José BernabéuU. de Valencia and IFIC
MODERN COSMOLOGY INFLATION, CMB and LSS
Centro de Ciencias deBenasque, August 2006
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
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 θ13 and δ
Feasibility and prospects
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.
Origin of masses
Why are Neutrino Masses so small?
even for a smooth LOG – scale…
i) With νL only, 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?
Origin of masses
UNIQUEDim. 5
Origin of masses
FΛ
vM
2
1. L = 2
2. F mixing, LFV
3. After SSB of Leff:
Conclusion
Lmass for “light” neutrinos GENERATED from Leff (at present energies)
and from L = 2 interactions at high energies Λ
• Origin of ? 1. Heavy mass R ?: conventional “See-Saw”
2. Fierz-reordering: other models
Leff → Lmass
“see –saw”
type
Why so light?
Maj
Maj
Neutrino mass matrix
The Pontecorvo MNS Matrix
3
2
1
Ue
100
0
0
0
010
0
0
0
001
1212
1212
1313
1313
2323
2323 cs
sc
ces
esc
cs
scUi
i
For Flavour oscillations U: 3 mixings, 1 phase
Atmospheric KEK More LBL-beams
Appearance e!Reactor Matter in Atmospheric…
SolarKAMLAND
Even if theyare Majorana
After diagonalization of the neutrino mass matrix,
Experiments 1998 - 2006
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
SNO solution: 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 νμ and ντ
KamLAND confirmation for reactor νe in terms of vacuum oscillations for long baseline detection
Experiments 1998-2006 Atmospheric neutrinos
Early deficit in the ratio N(νμ)/N(νe)
Zenith effect in SuperKamiokande: dependence for high
energy νμ neutrinos, 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 νμ to ντ
Confirmation from accelerator νμ K2K experiment:
survival probability + energy dependence
Neutrino flavour oscillations
2512
2
2323
2
108
104.2
eVm
eVm
What is known, what is unknown
81.02sin
00.12sin
122
232
o1013 ?
Majorana neutrinos ? 0: masses and phases
Absolute neutrino masses ? 3 H, Cosmology
Form of the mass spectrum Matter effect in neutrino propagation
First very recent results from MINOS
Energy resolutionin the detectorallows a bettersensitivity in Δm2
23 : compatible with previous resultswith some tendency to higher values
From Fermilab to Sudan, disappearance: L/E dependence
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.
Second generation approved experiments for U(e3) Appearance
experiments for the suppressed transition νμ νe : T2K, NOVA
Off-axis neutrino beamfrom Fermilab to Soudan From J-PARC to SK
Second generation approved experiments for U(e3) Disappearance experiment
from reactor νe: CHOOZ Double CHOOZ 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. Double Chooz will explore the range of sin2(2θ13) from 0.2 to 0.03-0.02, within three years of data taking.
Interest of energy dependence in suppressed neutrino oscillations
)4
sin(4
)4
cos(~
)4
(sin2sin
)4
(sin2sin)(
ceInterferen
213
212
213
Solar
2122
1222
23
cAtmospheri
2132
1322
23
E
Lm
E
Lm
E
LmJ
E
Lmc
E
LmsP e
Appearance probability:
|Ue3| gives the strength of Pe→νμ
After atmospheric and solar discoveries and accelerator and reactor measurements → 13 , CP violation accessible in suppressed appearance experiments
δ acts as a phase shift
CONCLUSION
1. SM Baryogenesis seems inefficient.2. Leptogenesis has all the good ingredients. It needs a
Majorana fermion at high scales.3. Any link to present neutrino physics? SEE-SAW connects m(L) with M(R).4. Leptogenesis depends on CP-odd M(R).5. Neutrino masses and mixings determined by m(L) CP-Violating Neutrino Oscillations.6. How to observe CP-phase? Phase-shift in suppressed e-neutrino mu-neutrino transition.
Interest of energy dependence in suppressed neutrino oscillations
CP violation: )()( ee PP
CPT invariance + CP violation = T non-invariance
)()( ee PP No Absorptive part Hermitian Hamiltonian
CP odd = T odd = is an odd function of time = L !
)()( ee PP
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!
Neutrinos from electron capture
Electron capture:
From the single energy e--capture neutrino spectrum,we can get a pure and monochromatic beam byaccelerating ec-unstable ions
2 body decay! a single discrete energy ifa single final nuclear level is populated
How can we obtain a monochromatic neutrino beam?
Forward directionZ protonsN neutrons
Z-1 protonsN+1 neutrons
boost
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.
Ion Candidates
Ions must have a mean life short enough to allowthem to decay in the storage ring before they loseits electron.
The recent discovery of nuclei that decay fast enoughthrough electron capture opens a window for realexperiments.
Implementation
Brief recall :
Ions produced at EURISOL
Accelerated by the SPS
Stored in a storage ring, straight sections point to detector
The facility would require a different approach to acceleration and storageof 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 willdiscuss have to have a half-life ≤ vacuum half-life ~ few minutes.
For the rest, setup similarto that of a beta-beam.
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.
)(4
*2
EQEdEd
dEC
00
22 1
ddE
d
JddE
d
LL
)cos1( LJ
Electron neutrino flux- For γ >>1 the neutrino flux in the forward direction is given by
Flux:Branching ratio
- 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.
Experimental Set-up
)(),;;()(18
),;( 1313 EEPENg
MEN
ee
CCA
d
),;( 13 EN
),( )0()0(13
-Number of muons produced in CC interactions in the detector at a fixed baseline L
Cross Section per water molecule
Statistical Analysis byCalculating
and fit to the value for the assumed parameters
by minimizing х2
),( )0()0(13
Experimental set-up
5 years 90 (close to minimum energy above threshold) 5 years = 195 (maximum achievable at present SPS)
Distance: 130 km(CERN-Frejus)
440 kton water ckov detector
Appearance &Disappearance
1018 decaying ions/year
OR … appropriate changes If higher production rates
Versus 10 years for each γ
Results for appearance and disappearance
Disentangling θ13 and δ
Much betterseparation for two different energies, evenwith lower statistics
Access to measure the CP phase as a phase-shift
The virtues of two energies
130 km
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
Exclusion plot: sensitivity
Total running time: 10 years... Impressive!! Significant even at 1o
013
Exclusion plot: δ ≠0 sensitivity
Total running time: 10 years... Significant for θ13 > 40
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.
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
CONCLUSION 1. SM Baryogenesis seems inefficient.2. Leptogenesis has all the good ingredients. It needs a
Majorana fermion at high scales.3. Any link to present neutrino physics? SEE-SAW connects m(L) with M(R).4. Leptogenesis depends on CP-odd M(R).5. Neutrino masses and mixings determined by m(L) CP-Violating Neutrino Oscillations.6. How to observe CP-phase? Phase-shift in suppressed e-neutrino mu-neutrino transition.