long baseline neutrino oscillations: theoretical aspects
DESCRIPTION
Long baseline neutrino oscillations: Theoretical aspects. NOW 2008 Conca Specchiulla, Italy September 9, 2008 Walter Winter Universität Würzburg. TexPoint fonts used in EMF: A A A A A A A A. Contents. Theoretical motivation: Quantities of interest How to measure these? - Phenomenology - PowerPoint PPT PresentationTRANSCRIPT
Long baseline neutrino oscillations:Theoretical aspects
NOW 2008 Conca Specchiulla, ItalySeptember 9, 2008
Walter WinterUniversität Würzburg
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Contents
Theoretical motivation:Quantities of interest
How to measure these? - Phenomenology Experiment choice and optimization Neutrino factory: what can we expect? The potentially unexpected Summary
Quantities of interest
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Theoretical motivation Mass models describe masses and mixings (mass
matrices) by symmetries, GUTs, anarchy arguments, etc.
From that: predictions for observables
Example: Literature research for 13
13 as performance indicator for models (Albright, Chen, 2006)
Talk: Mu-Chun Chen, Friday
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Large mixingsfrom CL and sectors?
Example: 23l = 12
= /4, perturbations from CL sector
(can be connected with textures) (Niehage, Winter, 2008)
Another example: QLC+Flavor symmetrieslead e.g. to
Modern QLC scenarios do not have an exact factor k=1 there (depends on model) (e.g. Plentinger, Seidl, Winter, 2008; see also: Frampton, Matsuzaki, 2008)
Some other examples
12l dominates 13
l dominates
12 ~ /4 + 13 cos CP 12 ~ /4 – 13 cos CP
13 > 0.1, CP ~ 13 > 0.1, CP ~
23 ~ /4 – (13)2/2 23 ~ /4 + (13)2/2
CP andoctant
discriminatethese
examples!
k as performance indicator for QLC modelsk
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Perform. indicators for theoryWhat observables test the theory space most efficiently?
Magnitude of 13 (see before!) Mass hierarchy
(strongly affects textures) Deviations from max. mixing
(- symmetry?) 23 octant |sin212-1/3|
(tribimaximal mixings?) |sinCP-1| (CP violation)
(leptogenesis?) Value of CP
k C+ 12 ~ /4 ~ 23 (k as indicator for quark-lepton unification models?)
Dev. from std. osc. framework
(Antusch et al, hep-ph/0404268)
Most important for LBL experiments
Long baseline phenomenology
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Why GeV energies?
Unoscillated flux Cross sections ~ E (DIS regime) Flux ~ E2 (beam collimation)
For fixed L: unoscillated event rate ~ E3
Oscillated flux Adjust baseline to stay on osc. maximum
Flux ~ 1/L2, L ~ E on oscillation maximumEvent rate ~ E on oscillation maximum
In addition:Matter effects (resonance energy ~ 10 GeV in Earth‘s mantle)Measure mass hierarchy, Flux(L) ~ const. at resonance
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GeV Long baseline experiments
Contamination
Source Production … and Detection Limitations L <E>
Beam,Super-beam
Intrinsic beam BGs,systematics
100-2,500 km
~ 0.5 – 5 GeV
Neutrino factory
Charge identification,NC BG
700-7,500 km
2-25 GeV
-beam Sourceluminosity
100-7,500 km
0.3 – 10 GeV
For leading atm. params Signal prop. sin2213
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Channels of interest
Disappearance for m312, 23:
NB: We expand in
Appearance for 13, CPV, MH: Golden: e (NF/BB) or e(SB)
(e.g., De Rujula, Gavela, Hernandez, 1999; Cervera et al, 2000)
Silver: e (NF – low statistics!?)(Donini, Meloni, Migliozzi, 2002; Autiero et al, 2004)
Platinum: e (NF: difficult!)(see e.g. ISS physics working group report)
Other appearance: (OPERA, NF?) Neutral currents for new physics
(e.g., Barger, Geer, Whisnant, 2004; MINOS, 2008)
31 = m312 L/(4E)
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Appearance channels
(Cervera et al. 2000; Freund, Huber, Lindner, 2000; Huber, Winter, 2003; Akhmedov et al, 2004)
Antineutrinos: Magic baseline: Silver: Superbeams, Plat.:
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Degeneracies
CP asymmetry
(vacuum) suggests the use of neutrinos and antineutrinos
One discrete deg.remains in (13,)-plane(Burguet-Castell et al, 2001)Burguet-Castell et al, 2001)
Additional degeneracies: Additional degeneracies: (Barger, Marfatia, Whisnant, 2001)(Barger, Marfatia, Whisnant, 2001) Sign-degeneracy Sign-degeneracy
(Minakata, Nunokawa, 2001)(Minakata, Nunokawa, 2001) Octant degeneracy Octant degeneracy
(Fogli, Lisi, 1996)(Fogli, Lisi, 1996)
Best-fit
-beam,
-beam, anti-
Iso-probability curves
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Degeneracy resolution Matter effects (sign-
degeneracy) – long baseline, high E
Different beam energies or better energy resolution in detector
Second baseline
Good enough statistics
Other channels
Other experimentclasses
Talk: Thomas Schwetz
WBB FNAL-DUSEL, T2KK, NF@long L, …
Monochromatic beam, Beta beam with different isotopes, WBB, …
T2KK, magic baseline ~ 7500 km, SuperNOvA
Neutrino factory, beta beam, Mton WC
SB+BB CERN-Frejus, silver/platinum @ NF
Atmospheric, …
(many many authors, see e.g. ISS physics WG report)(Minakata, Nunokawa, 2001; Parke)
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On-axis WBB versus off-axis NBBExample: NuMI-like beam 100kt liquid argon
CP=-/2
CP=+/2
sin2213 CP violation Mass hierarchy
(Barger et al, hep-ph/0703029)
Constraintfrom
NuMIbeam
FNAL-DUSELWBB
Ash RiverOA,NOvA*
Off-axis technology may not be necessary if the detector is good enough, i.e., has good BG rejection and good energy resolution! WC good enough???
On axis
C
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Quantification of performance
Commonly used performance indicators:Indicator Description + -
13 sensitivity (limit)
New 13 limit if no signal
Does not depend on (true) CP, MH
Strongly affected by degs (corresponds to worst case discovery reach)
13, CPV, MH discovery reach
Range of (true) 13 and CP for which 13, CPV, or MH can be discovered
Comprehensive picture of parameter space
Difficult to visualize: Depends on two true parameters
Sensitivity to octant
Range of (true) 13, 23 (and CP) for which the 23 octant can be established
Comprehensive picture of parameter space
Many true parameter dependencies
…
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Example: Discovery reaches… and the “Fraction of CP”
Sensitive region as function of true 13 and
CP
CP values now stacked for each 13
Read: If sin2213=0.04, we expect a discovery for
20% of all values of CP
Worst case 13 reach
Best case 13 reach
“Typical” CP:CP fraction 50%
Sometimes: Band for risk wrt CP
Simplifications:
Sometimes:choose specifc CP,
e.g. 3/2(worst/best case)
A
B
C
D E
F
G
Experiment choice and optimization (some thoughts)
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Small 13:Optimize 13, MH, and CPV discovery reaches in 13 direction
Large 13:Optimize 13, MH, and CPV discovery reaches in (true) CP direction
What defines “large 13”? A Double Chooz, Day Bay, T2K, … discovery? When?
Optimization of exps
(3m312=0.0022 eV2
Optimization for small 13
Optimization for large 13
T2KK
Beta beam
NuF
act
B
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Timescale for 13 discovery?
(Huber, Kopp, Lindner, Rolinec, Winter, 2006)
Assume:Decision on future experiments made after some LHC running and next-generation experiments
Two examples: ~ 2011: sin2213 > 0.04?
~ 2015: sin2213 > 0.01?
D
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Large 13 strategy
Assume that Double Chooz finds 13
Minimum wish listeasy to define: 5 independent confirmation of 13 > 0 3 mass hierarchy determination for any (true) CP
3 CP violation determination for 80% (true) CP
For any (true) 13 in 90% CL D-Chooz allowed range! What is the minimal effort (minimal cost) for that?
NB: Such a minimum wish list is non-trivial for small 13
NB: CP fraction 80% comes from comparison with IDS-NF baseline etc.
(arXiv:0804.4000(arXiv:0804.4000; Sim. from hep-ph/0601266; Sim. from hep-ph/0601266; 1.5 yr far det. + 1.5 yr both det.)1.5 yr far det. + 1.5 yr both det.)
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Example: Minimal beta beam
Minimal effort = One baseline only Minimal Minimal luminosity Any L (green-field!)
Example: Optimize L-for fixed Lumi: as large as 350
may not even be necessary!
(arXiv:0804.4000)(arXiv:0804.4000)
Sensitivity for entire Double Chooz allowed range!
5yr x 1.1 1018 Ne and 5yr x 2.9 1018 He useful decaysMore on beta beams: Mezzetto‘s talk!
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Small 13 strategy Assume that Double Chooz … do not find 13 Minimum wish list:
discovery of 13 > 0 3 mass hierarchy determination 3 CP violation determination
For as small as possible (true) 13 Two unknowns here:
For what fraction of (true) CP? One has to make a choice (e.g. max. CP violation, for 80% of all CP, for 50%, …)
How small 13 is actually good enough? Minimal effort is a matter of cost! Maybe the physics case will be defined
otherwise?
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Connection to high-E frontier?
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Optimal strategy vs. regional interests?
So far: purely conceptual …
… however, the optimal strategy depends on regional boundary conditions!
CERN-INO?JHF-INO?
Talk: Goswami
Talks:Goodman (US)Evans (MINOS)
Kurimoto (SciBooNE)
Talks:Ronga (Gran Sasso)
Scott-Lavina (OPERA)Sala (CNGS)
Talks:Kakuno (T2K)Dufour (T2KK)
Physics potential of the neutrino factory: what can we expect?
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International design study
IDS-NF: Initiative from ~ 2007-2012
to present a design report, schedule, cost estimate, risk assessment for a neutrino factory
In Europe: Close connection to „Eurous“ proposal within the FP 07
In the US: „Muon collider task force“
ISS
(Geer, 1997; de Rujula, Gavela, Hernandez, 1998; Cervera et al, 2000)
Signal prop. sin2213
Contamination
Muons decay in straight sections of a storage ring
Talks:Long (IDS-NF)Bonesini (R&D)
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IDS-NF baseline setup 1.0 Two decay rings E=25 GeV
5x1020 useful muon decays per baseline(both polarities!)
Two baselines:~4000 + 7500 km
Two MIND, 50kt each
Currently: MECC at shorter baseline (https://www.ids-nf.org/)(https://www.ids-nf.org/)
More by Ken Long
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Physics potential
3
BB B
Excellent 13, MH, CPV discovery reaches
About 10% full width error (3) on log10 (sin2213) for sin2213 = 0.001(Gandhi, Winter, hep-ph/0612158, Fig. 6)
About 20-60 degree full width error (3) on CP for sin2213 = 0.001 (Huber, Lindner, Winter, hep-ph/0412199, Fig. 7)
But what does that mean? Cabibbo angle-precision (C ~ 13 deg.)!
Why is that relevant? Can be another feature of nontrivial QLC models:E.g. from specific texture+QLC-type assumptions:
(: model parameter)
(Niehage, Winter, 2008)
(IDS-NF, 2007)
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Two-baseline optim. revisited
Robust optimum for ~ 4000 + 7500 km
Optimization even robust under non-standard physics(dashed curves)
(Kopp, Ota, Winter, 2008)
C
C
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Matter density measurement
Assume that only one parameter measured:Constant referencedensity Ref
or lower mantle density LM
(Minakata, Uchinami, 2007; Gandhi, Winter, 2007)
True =0
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Solar term:
Note that
i.e., effect (initially) increases with baseline ( ~ L)!
MSW effect sensitivity evenfor 13=0!
MSW effect in Earth matter
(hep-ph/0411309)
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C
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Octant degeneracy
4000 km alone: Problems with degs for intermediate 13
7200 km alone: No sensitivity for small 13
4000 km + 7200 km: Good for all 13
(Gandhi, Winter, 2007)
Similar performanceto Gold+Silver* @ 4000km
Meloni, arXiv:0802.0086
The unexpected!?
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~ current bound
Neutrino osc. framework incomplete?
Example: non-standard interactions (NSI) from effective four-fermion interactions:
Discovery potential for NSI-CP violation in neutrino propagation at the NF
Even if there is no CPV instandard oscillations, we mayfind CPV!
But what are the requirements for a model to predict such large NSI?
(arXiv:0808.3583)3
Talk by T. Ota
See also talk by D. Meloni
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Help from other experiments?
Physics scenario:Double Chooz finds 13and ~ a total of 100 muon tracks from astrophysical sources observed (ratio of muon tracks to showers), only m1 stableon extragalatic distances
Double Choozalone and this informationcould establish CPV
Other sources of information: Supernovae, atmospheric, LHC, 0
Talks: Petcov, Schwetz, Sigl, … (Maltoni, Winter, 2008)
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Outlook: How to design the optimal experiment
Future LBL experiment
Physics
Politics
Theory Performance indicators: 13, CP violation, MH, …Correlations+
Degeneracies Resolution strategies
New physics? Inclusive strategies(more channels, etc.)
Potitical boundary conditions
(e.g., Obama vs. McCain)
Same measurement
by other experiment
(e.g., MH from supernova)
Regionalinterests
(e.g., DUSEL, T2KK, …)
LHC(e.g.,connection to high-E frontier)