IFAE’06, Pavia, 19-21 Aprile 2006
Sommario della Sessione:
Neutrini e Raggi Cosmici
Conveners:
Laura Patrizii (INFN, Bologna)
Eligio Lisi (INFN, Bari)
Speakers:
Maximiliano Sioli (U. di Bologna)
Aldo Ianni (INFN, LNGS)
Marco Cirelli (Yale Univ.)
Flavio Gatti (INFN, Genova)
Maura Pavan (U. di Milano Bicocca)
Michele Frigerio (CEA/Saclay)
Alessandro Mirizzi (Univ. di Bari)
Davide Meloni (INFN, Roma I)
Michele Maltoni (ICTP, Trieste)
Giorgio Riccobene (INFN, LNS)
Daniel De Marco (U. of Delaware)
Andrea Chiavassa (Univ. di Torino)
Vincenzo Vitale (Univ. di Udine)
Paola Salvini (INFN, Pavia)
Neutrino masses, mixing and oscillations are
established facts
Super-K
m2-driven oscillations
KamLAND
m2-driven oscillations
(about half-period seen in both cases)
Frequencies and amplitudes can be embedded in a 3 framework
Current interpretation of world data (-LSND) stable
around the following scenario (with flavors e  ):
Abs.scale Normal hierarchy… OR… Inverted hierarchy
mass2 splittings
3
+m2
m 2
2
1
3
m2
-m2
A more quantitative summary
of world neutrino oscillation data
as of 2005 (with 2 errors)
2006, after MINOS (prelim.)
Good news for CNGS-OPERA,
since tau event rate ~(m2)2:
(2.6/2.4)2=1.17
Max Sioli (“Oscillazioni di neutrini con sorgenti artificiali”):
MINOS 2006
OPERA ~2006+5
(After MINOS: 12.8 x 1.17 = 15.0)
(2 , 3) oscillation parameters:
Significantly higher accuracy in next-generation
long-baseline experiments T2K, NOvA (Max Sioli)
(1 , 2) oscillation parameters:
Currently dominated by SNO (mixing) and by KamLAND
(mass2 difference). Some improvements expected in both expt.
Solar matter effects (MSW) with standard size (V = 2 GF Ne )
basically confirmed, but factor ~2 deviations still allowed
(from V(x)  aMSW V(x) with aMSW free)
Therefore, important to pursue spectroscopy
in the poorly known low-energy solar  range
(Aldo Ianni, “Oscillazioni di neutrini con sorgenti naturali”)
BOREXINO @ LNGS mission: Measure Be flux
…and maybe also (A. Ianni):
pep neutrinos with Borexino
•
•
Basic idea : reduce 11C
cosmogenic background
Method : tagging 11C by tackling
the produced (95%) neutrons in
spallation interactions
Strong competitors:
KamLAND (Be, pep)
SNO+ (pep)
Important to start the experiment as soon as possible …
The elusive mixing angle 13: current status
(Consistency of all data for small 13 is nontrivial)
The elusive mixing angle 13: future prospects
(Max Sioli)
13 fundamental to access mass hierarchy and leptonic CP violation
Hierarchy = sign(m2). In order to test the sign, we need
interference of oscillation phase (m2 L/E) with another
“phase” Q having known sign. Two options (barring exotics):
Q driven by matter effects (only in matter & for s13>0)
Q driven by m2
(in any case, but very hard!)
Basically all current projects focus on the first option
Abs.scale Normal hierarchy… OR… Inverted hierarchy
mass2 splittings
3
+m2
m 2
2
1
3
m2
-m2
If nature is kind enough, this option might be exploited in
the next galactic supernova explosion (~3/century)
(Alessandro Mirizzi, “Fisica dei neutrini da Supernova”)
E.g., observation of non-monotonic
time spectra through inverse beta
decay in water-Ch. detectors would:
1) Establish inverse hierarchy
2) Monitor the SN shock wave
3) Establish a lower bound on sin213
(with sensitivity down to 10-4)
13 fundamental to access also leptonic CP violation (which vanishes
when the full 3 parameter space is reduced to an effective 2 one).
If 13 nonzero, however, attempts to determine 13 and CP
in future long-baseline experiments must face the occurrence of
multiple solutions (“degeneracies” or “clones”), as discussed by
Davide Meloni and Michele Maltoni
Several ways out have been explored through prospective simulations
E.g., by combining different appearance channels at
a future neutrino factory:
2- golden+silver channels
solo golden
(Davide Meloni, “Violazione di CP nel settore leptonico”)
Or, by combining future long-baseline accelerator
and atmospheric neutrino data:
(Michele Maltoni, “Sinergie fra neutrini da acceleratore e atmosferici”)
Absolute neutrino mass observables: (m, m, )
1)
 decay: m2i  0 can affect spectrum endpoint. Sensitive to
the “effective electron neutrino mass” (Flavio Gatti):
2) 02 decay: Can occur if m2i  0 and =. Sensitive to the
“effective Majorana mass” and phases (Maura Pavan):
3) Cosmology: m2i  0 can affect large scale structures in (standard)
cosmology constrained by CMB+other data (Marco Cirelli). Probes:
Italian contribution to calorimetric spectroscopy and m limits, in perspective
(Flavio Gatti)
2 eV
20 eV
1990
0.2 eV
1995
MAINZ
2000
2005
2010
2015
2.2 eV
20-10 eV
KATRIN
TROITZK
spettrometri
magnetici
spettrometri
elettrostatici
2.2 eV
Spettrometri
Calorimetri
26 eV95%CL
Sandro Vitale
1985
187Re
1990
MANU
MARE
15 eV90%CL
MIBETA
20 eV
1995
2000
2005
2 eV
2010
0.2 eV
2015
Italian contributions to m searches: Pioneering +… Cuoricino, Cuore, Gerda …
(Maura Pavan)
130 Te:
Cuoricino NOW
02
2530 keV
started in April 2003
long interruption for maintenance
1/20 > 2 10 24 y at 90% C.L.
<m> < 0.3-0.7 eV
Cuoricino within 3 years
<m>
<
0.2-0.5 eV
Constraints on  from CMB + Large Scale Structure data
(Marco Cirelli)
Oscillations fix the mass splittings and thus induce
positive correlations between any pair of the three
observables (m, m, ), e.g.:
m

i.e., if one observable increases, the other one
(typically) also increases
Oscillation data only:
Positive
correlations
Partial overlap
between
NH and IH
Large (intrinsic)
m spread due
to unknown
Majorana phases
Current info from non-oscillation experiments:
1)
 decay: no signal so far. Mainz & Troitsk expts: m < O(eV)
2)
02 decay, no signal in all experiments, except in the most
sensitive one to date (Heidelberg-Moscow). Rather debated claim.
Claim accepted: m in sub-eV range (with large uncertainties)
Claim rejected: m < O(eV).
3)
Cosmology. Upper bounds:  < eV/sub-eV range, depending
on several inputs and priors. E.g., Lyman- data crucial to
reach sub-eV bounds (but: systematics?)
02 claim rejected: cosmological bound dominates
[Green dotted line: a more aggressive <0.3 eV bound]
02 claim accepted: tension with cosmological bound(s)
} expt+theo error
(Green dotted line:
<0.3 eV )
No reasonable combination at face value, but: too early to draw definite conclusions
Absolute masses, hierarchy, CP violation, Majorana/Dirac nature, more
accurate oscillation parameters also crucial to constrain model building
(Michele Frigerio, “Modelli teorici per le masse dei neutrini”)
… together with the possible connections with other sectors of physics …
… including Higgs physics (Michele Frigerio)
… or cosmology, with radically new ideas (Marco Cirelli)
In both cases, we need to understand fundamental scalar fields and
their couplings, and we all hope to open this window with the LHC!
Dreaming about future, precise nonoscillation + oscillation data …
Check overall
consistency …
Identify the
hierarchy …
Probe the
Majorana
phases …
(and the CP
phase too…)
Cosmic Rays -> Laura Patrizii