cp violation and mass hierarchy searches neutrinos in particle physics and astrophysics (lecture)...
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CP violation and mass hierarchy searches
Neutrinos in particle physics and astrophysics (lecture)
June 2009
Walter WinterUniversität Würzburg
2
Contents
Phenomenology Simulation tools Experiments and CP violation
measurement CP precision measurement CPV from non-standard physics? Mass hierarchy measurement Summary
Phenomenology
(partly repetition from lecture)
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Neutrino mixing with three flavors
( ) ( ) ( )= xx
(sij = sin ij cij = cos ij)Potential CP violation
From observations:
• 23, 12 large
• 13 small, unknown
Atmospheric mixing Reactor mixing Solar mixing
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Neutrino masses: three flavors
Normal or inverted mass ordering
Neutrino oscillations driven by |m31
2| (atm.) >> m212 (solar)
Flavor content in mass eigenstate i given by |Ui|2
Absolute mass scale unknown (< eV): Tritium endpoint Neutrinoless double beta decay Cosmology
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8
Normal Inverted
|Ue3|2 ~ s132
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Three Flavors: six parameters(three angles, one phase; two independent mass squared differences)
Describes atmospheric, solar, reactor data in two flavor limits:
Neutrino oscillations
Coupling: 13
Atmospheric oscillations:Amplitude: 23
Frequency: m312
Solar oscillations:Amplitude: 12
Frequency: m212
Suppressed
effect: CP
(Super-K, 1998;Chooz, 1999; SNO 2001+2002; KamLAND 2002)
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Two flavor limits (lecture!) Atmospheric neutrinos
Solar neutrinosAdiabatic evolution (MSW), mostly sensitive to 12
Reactor experiments Atmospheric oscillation length (L ~ 1-2 km)
Solar oscillation length (L ~ 30-100 km)
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Three flavor effectsWith the following definitions
expand to second order in small quantities and 13:
Test: for = 0, 13 = 0: Pe = 0Problem: The info has to be disentangled from this expression!
Masshierarchy!
Quantities of interest
Spectral terms
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CP violation (CPV)
CP violation: Matter and antimatter behave „differently“ (in a well defined way including the peculiarities of the Standard Model, i.e., V-A interactions)
Necessary requirement for baryogenesis Here: CP violation ~ Im (ei) ~ sin CP
Define: we discover CP violation if we can exclude CP = 0 and (where sin CP=0, or U is real) at the chosen confidence level
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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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CPV - statistics
2(12,13,23,,m212,m31
2)
For future experiments: we have to simulate data (Oi) assuming a set of (12,13,23,,m21
2,m312)
implemented by nature: „true values“, „simulated values“
Mostly the unknown 13 and relevant
Compute 2(13,)=Min12,13,23,m212,m312 2(12,13,23,0/,m21
2,m312
,13,)
(marginalization over unwanted parameters) Discovery potential as a function of (13,)
Our „theory“ (fit values), describe Ti
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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
Best performanceclose to max.
CPV (CP = /2 or 3/2)
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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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The magic baseline
Simulation tools
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GLoBES
AEDL„Abstract ExperimentDefinition Language“
Define and modifyexperiments
AEDL files
User InterfaceC library,
loads AEDL files
Functionality for experiment simulation
Simulation of futureexperiments
http://www.mpi-hd.mpg.de/lin/globes/
(Huber, Lindner, Winter, 2004;Huber, Kopp, Lindner, Rolinec, Winter, 2006) Application software
linked with user interfaceCalculate sensitivities etc.
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Event rate engine
In practice: Secondary particles
integrated out
Detector response R(E,E´)
E E´
E: Incident neutrino energyE‘: Reconstructed energyE: Secondary particle energy(e.g. muon)
Experiments andCP violation measurement
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There are three principle possibilities to artificially create neutrinos:
Beta decay:Example: Nuclear fission reactors
Pion decay:From accelerators:
Muon decay:The muons are produced by pion decays!
Muons,Neutrinos
Reminder: „man-made“ neutrinos
Protons
Target Selection,Focusing
Pions
Decaytunnel
Absorber
Neutrinos
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Next generation experiments
Perspectives to constrain 13 and find CPV relatively weak
Focus on next-to-next generation!Example: Neutrino factory
(Huber, Lindner, S
chwetz, W
inter, in prep.)
CL
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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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NF physics potential 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; see also: Gandhi, Winter, 2007)
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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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On near detectors@IDS-NF
Define near detectors including source/detector geometry: Near detector limit:
Beam smaller than detector Far detector limit:
Spectrum similar to FD Compute spectrum, study
systematical errors, study impact of physics
(Tang, Winter, arXiv:0903.3039)
~ND limit ~FD limit
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Example: Systematics(Tang, Winter, arXiv:0903.3039)
CP precision measurement
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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
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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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: difficult to 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, lepton universality 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
Mass hierarchy (MH)
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Motivation
Specific models typically come together with specific MH prediction (e.g. textures are very different)
Good model discriminator(Albright, Chen, hep-h/0608137)
8
8
Normal Inverted
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Magic baseline:Removes all degeneracy issues (and is long!)
Resonance: 1-A 0 (NH: , IH: anti-)Damping: sign(A)=-1 (NH: anti-, IH: )Energy close to resonance energy helps (~ 8 GeV)
To first approximation: Pe ~ L2 (e.g. at resonance)Baseline length helps (compensates 1/L2 flux drop)
Matter effects
(Cervera et al. 2000; Freund, Huber, Lindner, 2000; Huber, Winter, 2003; Akhmedov et al, 2004)
Lecture:
39
Baseline dependence
Comparison matter (solid) and vacuum (dashed)
Matter effects (hierarchy dependent) increasewith L
Event rate (, NH) hardly drops with LGo to long L!
(Freund, Lindner, Petcov, Romanino, 1999)
(m212 0)
Eve
nt
rate
s (A
.U.)
Vacuum, NH or IH
NH matter effect
NH matter effect
40
Mass hierarchy sensitivity
For a given set of true 13 and CP: Find the sgn-deg.solution
Repeat that for all true true 13 and CP (for this plot)
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Small 13 optimization: NF
Magic baseline good choice for MH E ~ 15 GeV sufficient (peaks at 8 GeV)
(Huber, Lindner, Rolinec, Winter, 2006) (Kopp, Ota, Winter, 2008)
E-L (single baseline) L1-L2 (two baselines)
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Summary
CP violation measurement requires next-to-next generation of experiments
Example: Neutrino factory Other relevant quantities:
CP precision measurement CP violation from non-standard physics Mass hierarchy
CP violation discovery in the lepton sector may be an interesting hint for leptogenesis!
This talk at: http://www.physik.uni-wuerzburg.de/~winter/Teaching/neutrinos.html