cp violation searches with neutrino factories and beta beams
DESCRIPTION
CP violation searches with Neutrino Factories and Beta Beams. Neutrinos in Particle, in Nuclear and in Astrophysics Trento, Italy November 20, 2008 Walter Winter Universität Würzburg. TexPoint fonts used in EMF: A A A A A A A A. Contents. Motivation from theory CPV Phenomenology - PowerPoint PPT PresentationTRANSCRIPT
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CP violation searches with Neutrino Factories and Beta Beams
Neutrinos in Particle, in Nuclear and in AstrophysicsTrento, ItalyNovember 20, 2008
Walter WinterUniversität Würzburg
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Contents
Motivation from theory CPV Phenomenology CP precision measurement CPV from non-standard physics Summary
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Motivation from theory
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Where does CPV enter? Example: Type I seesaw (heavy SM singlets Nc)
Charged leptonmass terms
Eff. neutrinomass terms
Block-diag.
CC
Primary source of CPV(depends BSM theory)
Effective source of CPV(only sectorial origin relevant)
Observable CPV(completely model-indep.)
Could also be type-II, III seesaw,
radiative generation of neutrino mass, etc.
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From the measurement point of view:It makes sense to discuss only observable CPV(because anything else is model-dependent!)
At high E (type I-seesaw): 9 (MR)+18 (MD)+18 (Ml) = 45 parameters
At low E: 6 (masses) + 3 (mixing angles) + 3 (phases) = 12 parameters
Connection to measurement
There is no specific connectionbetween low- and
high-E CPV!
But: that‘s not true for special (restrictive) assumptions!
CPV in 0 decayLBL accessible CPV: If UPMNS real CP conserved
Extremely difficult! (Pascoli, Petcov, Rodejohann, hep-ph/0209059)
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Why is CPV interesting?
Leptogenesis:CPV from Nc decays
If special assumptions(such as hier. MR,NH light neutrinos, …)it is possible that CP
is the only source ofCPV for leptogensis!
(Nc)i (Nc)i
~ MD (in basis where
Ml and MR diagonal)
(Pascoli, Petcov, Riotto, hep-ph/0611338 )Different curves:different assumptions for 13, …
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How well do we need to measure?
We need generic argumentsExample: Parameter space scan for eff. 3x3 case (QLC-type assumptions, arbitrary phases, arbitrary Ml)
The QLC-type assumptions lead to deviations O(C) ~ 13
Can also be seen in sum rules for certain assumptions, such as
(: model parameter) This talk: Want Cabibbo-angle order precision for CP!
(Niehage, Winter, arXiv:0804.1546)
(arXiv:0709.2163)
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CPV phenomenology
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Terminology
Any value of CP
(except for 0 and )violates CP
Sensitivity to CPV:Exclude CP-conservingsolutions 0 and for any choiceof the other oscillationparameters in their allowed ranges
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Measurement of CPV
(Cervera et al. 2000; Freund, Huber, Lindner, 2000; Huber, Winter, 2003; Akhmedov et al, 2004)
Antineutrinos: Magic baseline: Silver: Platinum, Superb.:
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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
Antineutrinos
Iso-probability curves
Neutrinos
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Intrinsic vs. extrinsic CPV The dilemma: Strong matter effects (high E, long L),
but Earth matter violates CP Intrinsic CPV (CP) has to be
disentangled from extrinsic CPV (from matter effects)
Example: -transitFake sign-solutioncrosses CP conservingsolution
Typical ways out: T-inverted channel?
(e.g. beta beam+superbeam,platinum channel at NF, NF+SB)
Second (magic) baseline(Huber, Lindner, Winter, hep-ph/0204352)
NuFact, L=3000 km
Fit
True CP (violates
CP maximally)
Degeneracy above 2
(excluded)
True
Critical range
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CPV discovery reach … in (true) sin2213 and CP
Sensitive region as a
function of true 13 and CP
CP values now stacked for each 13
Read: If sin2213=10-3, we
expect a discovery for 80% of all values of CP
No CPV discovery ifCP too close to 0 or
No CPV discovery forall values of CP3
Cabibbo-angleprecision for CP
~ 85%!Fraction 80% (3)
corresponds to Cabibbo-angleprecision at 2 BENCHMARK!
Best performanceclose to max.
CPV (CP = /2 or 3/2)
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CPV as a fct. of 13
General structure: Signal
Even without systematics (NC, mis-ID, …):
For sin2213 << 2 ~ 10-3
Lose sensitivity with sin 213
For sin2213 >~ 2 ~ 10-3
Sensitivity almost constant over wide range of 13
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Small 13:Optimize discovery reach in 13 direction
Large 13:Optimize discovery reach in (true) CP direction
What defines “small” vs “large 13”? A Double Chooz, Day Bay, T2K, … discovery?
Optimization for CPV
Optimization for small 13
Optimization for large 13
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Large 13 strategy
Assume e.g. that Double Chooz discovers 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
(~ 2 sensitvity to a Cabibbo angle-size CP violation)
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
(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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More recent modifications: Higher (Burguet-Castell et al, hep-ph/0312068)
Different isotope pairs leading to higher neutrino energies (same )
Beta beam concept… originally proposed for CERN
(http://ie.lbl.gov/toi)
Key figure (any beta beam):Useful ion decays/year?
Often used “standard values”:3 1018 6He decays/year1 1018 18Ne decays/year
Typical ~ 100 – 150 (for
CERN SPS) eFeNe 189
1810
eLiHe 63
62
(CERN layout; Bouchez, Lindroos, Mezzetto, 2003; Lindroos, 2003; Mezzetto, 2003; Autin et al, 2003)
(Zucchelli, 2002)
(C. Rubbia, et al, 2006)
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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:CPV constrains
minimal as large as 350
may not even be necessary!(see hep-ph/0503021)
CERN-SPS good enough?
(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 decays
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Example: low-E NuFact A low-E NuFact
performs similarly Combination with
platinumchannel or superbeam may help
(from: Huber, Winter, arXiv:0706.2862; also: Geer, Mena, Pascoli, hep-ph/0701258; Bross et al, arXiv:0708.3889)
Benchmark: 80% 3
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Assume that Double Chooz … do not find 13 Example: Beta beam in 13-direction (for max. CPV)
„Minimal effort“ is a matter of cost!
Small 13 strategyExample: Beta beams
(Huber et al, hep-ph/0506237) (Agarwalla et al, arXiv:0802.3621)
50 kt MIDL=400 km
LSF ~ 2
(LSF)
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Neutrino factory: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
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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/)
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CPV physics potential
3 Excellent 13, MH, CPV discovery reaches (IDS-NF, 2007)
Robust optimum for ~ 4000 + 7500 km
Optimization even robust under non-standard physics(dashed curves)
(Kopp, Ota, Winter, arXiv:0804.2261)
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Experiment comparison
The sensitivities are expected to lie somewhere between the limiting curves
Example: IDS-NF baseline(~ dashed curve)
(ISS physics WG report, arXiv:0810.4947, Fig. 105)
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CP precision measurement
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Theoretical exampleLarge mixingsfrom CL and sectors?
Example: 23l = 12
= /4, perturbations from CL sector
(can be connected with textures) (Niehage, Winter, arXiv:0804.1546; see also Masina, 2005; Antusch, King 2005 for similar sum
rules) The value of CP is interesting (even if there is no CPV)
Phenomenological exampleStaging scenarios: Build one baseline first, and then decide depending on the outcome Is CP in the „good“ (0 < CP < ) or „evil“ ( < CP < 2) range?
(signal for neutrinos ~ +sin CP)
Why is that interesting?
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!
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Performance indicator: CP coverage
Problem: CP is a phase (cyclic)
Define CP coverage (CPC):Allowed range for CP which fits a chosen true value
Depends on true 13 and true CP
Range: 0 < CPC <= 360
Small CPC limit:Precision of CP
Large CPC limit:360 - CPCis excluded range
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CP pattern
Performance as a function of CP (true)
Example: Staging.If 3000-4000 km baseline operates first, one can use this information to determine if a second baseline is needed
(Huber, Lindner, Winter, hep-ph/0412199)
Exclusion limitPrecision limit
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CPV from non-standard physics?
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~ current bound
CPV from non-standard interactions
Example: non-standard interactions (NSI) in matter from effective four-fermion interactions:
Discovery potential for NSI-CPV 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
IDS-NF baseline 1.0
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CPV discovery for large NSI
If both 13 and |em|
large, the change to discover any CPV will be even larger: For > 95%of arbitrary choices of the phases
NB: NSI-CPV can also affect the production/detection of neutrinos(Gonzalez-Garcia et al, hep-ph/0105159; Fernandez-Martinez et al, hep-ph/0703098; Altarelli, Meloni, 0809.1041) (arXiv:0808.3583)
IDS-NF baseline 1.0
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Effective operator picture:
Describes additions to the SM in a gauge-inv. way! Example: NSI for TeV-scale new physics
d=6: ~ (100 GeV/1 TeV)2 ~ 10-2 compared to the SMd=8: ~ (100 GeV/1 TeV)4 ~ 10-4 compared to the SM
Current bounds, such as from CLFV: one cannot construct large (= observable) leptonic matter NSI with d=6 operators (except for
m, maybe)
(Bergmann, Grossman, Pierce, hep-ph/9909390; Antusch, Baumann, Fernandez-Martinez, arXiv:0807.1003; Gavela, Hernandez, Ota, Winter,arXiv:0809.3451)
Need d=8 effective operators!Finding a model with large NSI is not trivial!
Models for large NSI?
mass d=6, 8, 10, ...: NSI
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Systematic analysis for d=8
Decompose all d=8 leptonic operators systematicallyThe bounds on individual
operators from non-unitarity, EWPD, etc are very strong! (Antusch, Baumann, Fernandez-Martinez, arXiv:0807.1003)
Need at least two mediator fields plus a number of cancellation conditions(Gavela, Hernandez, Ota, Winter, arXiv:0809.3451)
Basis (Berezhiani, Rossi, 2001)
Combinedifferent
basis elements
C1LEH, C3
LEH
Canceld=8
CLFV
But these mediators cause d=6 effects Additional cancellation condition
(Buchmüller/Wyler – basis)
Avoid CLFVat d=8:
C1LEH=C3
LEH
Feynman diagrams
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Summary
The Dirac phase CP is probably the only realistically observable CP phase in the lepton sectorMaybe the only observable CPV evidence for leptogenesisThis and 1, 2: the only completely model-inpendent
parameterization of CPV What precision do we want for it? Cabibbo-angle
precision? Relates to fraction of „CP“ ~ 80-85% The perspectives for a measurement are best if 13 is
not too small and not too large For a BB or NF, the experiment optimization/choice
depends on 13 large or small Other interesting aspects in connection with CPV:
CP precision measurement, NSI-CPV
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Backup
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Minimal beta beam at the CERN-SPS?( fixed to maximum at SPS)
(arXiv:0809.3890)(arXiv:0809.3890)
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Appearance ratesNF Golden-SB appearance-NF Platinum
Ep chosen such that SB peaks at lower E Platinum peaks at higher E (spectrum!)
(Huber, Winter, 2007)
2.5 102.5 10
2121 useful muon decays
useful muon decays
Golden
E=5 GeVL=1250 km
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Low-E Nufact optimization
Geer et al. choices are sufficiently close to optimum NF-SB synergistic, better performance than NF alone Our choices : L = 900 km, E = 5 GeV and L=1250 km, E=5 GeV
(given the low energy ~ minimum effort constraint)
CP
fraction for discovery (3) , sin
2213 =
0.1
(Huber, Winter, 2007)
Doubleluminosity!
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(Mats Lindroos)
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(Mats Lindroos)