1. Neutrino mass and mixing: 2006 Status1
NOW 2006
Conca Specchiulla, Otranto
Neutrino
mass and mixing:
2006 Status
Antonio Palazzo
University of Oxford
and
INFN, Bari
based on work done in collaboration with:
G.L. Fogli, E.Lisi, A. Marrone (Bari)
A. Melchiorri, P. Serra (Rome)
J. Silk , A. Slosar (Oxford)

2. • Introduction: The 3 framework 2
Outline
• Introduction: The 3 framework
• Constraints on oscillation parameters
• Constraints on absolute  masses
• Combination of world n data (when feasible)
• Conclusions

3. Mass spectrum Mixing Sensitivities3
Mass spectrum
Norm. Hier.
Inv. Hier. n3 n2
m2
- Absolute mass scale not
probed by  oscillations n1 ?
+Dm2
-Dm2 n2
- Hierarchy unknown
m2 n1 n3
Mixing
Sensitivities
leading 2
S12 ~ 0.31
- Solar, KamLAND
(dm2, q12, q13)
sub-leading 2
S23 ~ 0.45
- ATM, K2K, MINOS
(Dm2, q23, q13)
S13 < few% 2
- CHOOZ
(Dm2, q13)
* Hint for a third DM2 ~O(eV2) from LSND: waiting for MiniBoone (dis)confirmation .

4. leading “solar” parameters4
Constraints on the
leading “solar” parameters

5. Consistency among four LMA essentially determined by5
2n Solar constraints
Consistency among four
different experiments
LMA essentially determined by
SNO + SK
sensitive to
high energy 8B n’s

6. LMA solution confirmed by KamLAND6
LMA solution confirmed by KamLAND
Disappearance
Spectral distortions 2 4 6 8

7. 2n Solar + KamLAND contraints7
2n Solar + KamLAND contraints
Very high level of consistency
KamLAND dominates
dm2 constraints
q12 range determined
by solar data

8. Matter effects with standard size confirmed8
Matter effects with standard size confirmed
V(x) = 2 GF Ne(x)
V(x) aMSW V(x)
(dm2,q12) marginalized

9. leading “atmospheric” parameters9
Constraints on the
leading “atmospheric” parameters
(pre-MINOS)

10. Super-Kamiokande Evidence for atmospheric nm-> nt oscillations10
Super-Kamiokande
Evidence for atmospheric
nm-> nt oscillations
angle dependence
in zenith distributions
oscillatory pattern
no osc.
in high L/E resolution analysis

11. confirmed by K2K: The first LBL accelerator experiment11
confirmed by K2K: The first LBL accelerator experiment
K2K energy spectrum
No oscillation
Best fit
Both
nm disappearance
and
spectral distortion
observed
No oscillation
(normalized to data)
Number of events
En (GeV)

12. Constraints from the 2n analysis12
Constraints from the 2n analysis
Stringent constraints from SK
Perfect agreement with K2K
Dm2 range determined
with a 24% accuracy (2s)
Contours at 1, 2, 3  (1 dof)

13. 13
Limits on 13

14. CHOOZ and the upper bound on q1314
CHOOZ and the upper bound on q13
Non observation of
ne disappearance
exclusion plot in the
(m2, 13) plane
m2 scale set by
SK+K2K+(MINOS)
Upper limit on q13
Anti-correlation between
13 upper limit and m2

15. stable for unconstrained 13 Mild anti-correlation15
3n CHOOZ + (SK + K2K) constraints
Strong upper bound on q13
Leading parameters
stable for unconstrained 13
Mild anti-correlation
between Dm2 and q13

16. 3n Solar + KamLAND constraints16
3n Solar + KamLAND constraints
Solar and KamLAND
prefer q13 = 0
Leading parameters
stable for
unconstrained 13
Upper limit on q13
dominated
by solar data …

17. Gallium-SNO : tension for q13 = 017
Gallium-SNO : tension for q13 = 0
SNO and Gallium: 3n constraints (1s)
perfect agreement for q13 = 0 spoiled for increasing q13
See also Goswami & Smirnov , Phys.Rev.D (2005) (hep-ph/ )

18. 18
Impact of MINOS

19. MINOS first results: Corroborate SK and K2K19
MINOS first results: Corroborate SK and K2K
735 Km
MINOS energy spectrum
(hep-ex/ )

20. …and improve parameters’ determination20
…and improve parameters’ determination
POST - MINOS
PRE - MINOS
Dm2 noticeable improvement from 24% to 15% (2s)
q23 still dominated by atmospheric (SK)
q13 upper bound slightly improved

21. Overview of the global analysis constraints21
Overview of the global analysis constraints

22. up-to-date numerical ±2 ranges22
up-to-date numerical ±2 ranges

23. Constraints on absolute  masses23
Constraints on
absolute  masses

24. Current limits: (Mainz + Troitsk) upper bound m < 1.8eV (2s)24
 decay: mi  0 can affect the spectrum endpoint
Observable: “effective electron neutrino mass”
Current limits: (Mainz + Troitsk) upper bound m < 1.8eV (2s)

25. Observable: “effective Majorana mass”25
Neutrinoless double b decay (02) : possible if mi  0 and n = n
(Z, A)  (Z+2, A) + 2e- Q
22b n p e-
= W
02b
Observable: “effective Majorana mass”
Majorana phases
No signal in all experiments, except for the claim of Klapdor et al. (Heidelberg-Moscow)
claim accepted, m in the range [ ] eV (2s)*
claim rejected, m < 0.81eV
* Theoretical input for nuclear matrix elements taken from Rodin et al. (2006).

26. Sensitivity up to S < 0.17eV (2s)26
Cosmology: mi  0 can affect LSS and CMB
massive n’s suppress the formation of small scale structures
mn = 0
1 eV
7 eV
4 eV
Observable: sum of neutrino masses
Current limits: depend on the dataset considered.
Sensitivity up to S < 0.17eV (2s)
Ma, 1996

27. Results from the analysis of cosmological data27
Results from the analysis of cosmological data
Bounds
obtained with seven
different data sets
data set
2s limit
1- WMAP eV
2- WMAP + SDSS eV
3- WMAP + SDSS + SN + HST + BBN eV
4- WMAP + LSS + SN eV
5- WMAP + LSS + SN + BAO eV
6- WMAP + LSS + SN + Ly-a eV
7- WMAP + LSS + SN + BAO + Ly-a eV

28. superposed constraints on (mb, m, )28
superposed constraints on (mb, m, )
n oscillations
- Significant correlations
- Partial overlap of NH and IH
- Large m spread
- Lower bound on S
b decay
Irrelevant in all cases
except when combined with
the less stringent cosmo data set (1)
Tension between
Cosmology and 0n2b claim …

29. 0n2b claim with cosmological bounds29
combination of
0n2b claim with cosmological bounds
not feasible
most “aggressive”
data set (7)
we disregard most of
the cosmological data
and consider
only the WMAP results
… unless

30. Only an another 0n2b experiment with higher sensitivity 30
However,
we should not be too hasty in concluding that :
“cosmological data rule out the claim of Klapdor et al.,”
since:
- The 0n2b signal might be due to new physics beyond light Majorana n’s
- Astrophysical data may be still affected by unknown systematics
- Bounds on S unavoidably depend on assumptions on the Cosmological Model
Only an another 0n2b experiment
with higher sensitivity
can (dis)prove such claim

31. absolute neutrino masses31
Conclusions
flavor oscillations
- All the existing data* fit perfectly within a 3n framework
- Basic parameters determined with a [10-30]% accuracy
- Latest major improvement coming from MINOS (24%  15% on Dm2)
absolute neutrino masses
- Cosmology most sensitive probe at the moment
providing sub-eV upper bounds
- Tension with the Heidelberg-Moscow claim
requires further scrutiny in both fields
- b decay: promising (KATRIN)
* Except for LSND