Transcript Physics potential of very long neutrino factory baselines

Physics working group summary
2nd ISS Meeting
KEK, Tsukuba, Japan
January 23-25, 2006
Walter Winter
Institute for Advanced Study, Princeton
For the ISS physics working group
Contents
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Introduction
Meeting summary:
– Theory (… and muon physics)
– Phenomenology:
Non-accelerator measurements and “new physics”
– Physics with a superbeam, beta beam,
neutrino factory
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Towards the final product:
Performance indicators and presentation of results?
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Open questions, next steps
Summary
Jan. 24+25, 2006
ISS KEK Summary - Walter Winter
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Three-flavor oscillations: Requirements
Atmospheric
oscillation:
Amplitude: q23
Frequency: Dm312
Solar
oscillation:
Amplitude: q12
Frequency: Dm212
Subleading
effect: dCP
Coupling strength: q13
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Neutrino oscillation parameters (1s):
Dm212 ~ 8.2 10-5 eV2
+- 5%
sin22q12 ~ 0.83 +- 5%
|Dm312| ~ (2 – 2.5) 10-3 eV2
sin22q23 ~ 1
+- 7%
sin22q13 < 0.14
Superbeam/n-factory/
dCP = ?
Beta Beam
Mass hierarchy?
Jan. 24+25, 2006
Key to subleading
effects (CP violation,
mass hierarchy)
(see e.g. Bahcall et al, hep-ph/0406294;
Super-K, hep-ex/0501064;
CHOOZ+solar papers)
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Theory
(plus some muon physics)
Why are the parameters, which we
want to study, interesting at all?
(more specific versions
of “big questions”)
(Murayama)
Flavor symmetry?
(Murayama)
Same gauge quantum numbers, but mass hierarchy and
small mixings “unnatural” (for quarks, charged leptons)
 Hidden quantum number?
Symmetry
“Flavor symmetry”
Emmy Noether
Conserved quantity
Hidden quantum number
Same for neutrino generations, different for charged
leptons, quarks?
Break flavor symmetry by small VEV
 Hierachies, e.g., mu:mc:mt ratio
Atmospheric mixing maximal+two large mixing angles
 How big quantitatively? From anarchy: q13 not too small?
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(Minakata)
Quark-Lepton complementarity?
Understand phenomenological relationships
between quarks and leptons at deeper level
 Example:
 Deeper underlying reason or accidental?
 Note: CKM/MNS
matrix is composited
of two parts
 Implement QLC?
Important in future:
parameter precision measurements!
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Jan. 24+25, 2006
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(Fukugita)
Massive neutrinos in cosmology
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Two applications: Leptogenesis and mass bounds
Evolution of large scale structure
well understood; massive
neutrinos damp fluctuations
on horizon scale; power spectrum!
Bounds from different
combinations of CMB, galaxy
clustering, cluster abundance,
grav. Lensing, Lyman a
Limits: 2 eV (CMB alone, robust)
0.42 eV (use of Lyman a) – but: systematics issue?
Future: e.g. large cluster surveys (> 100,000) 0.03 eV!
Jan. 24+25, 2006
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(Hisano)
Flavor physics to establish SUSY?
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Probe origin of SUSY breaking terms and models
beyond MSSM
from studies of flavor and CP violation
Charged LFV (e.g. m -> e g) + neutrino oscillations
provide independent information on see-saw;
large mixing angles might enhance charged LFV;
especially q13 measurement would allow
predictions of charged LFV
Good example for accumulating complementary
hints from different experiments to obtain clearer
picture of physics
Jan. 24+25, 2006
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(Kuno)
(Towards) search for charged lepton
mixing at NuFact
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Charged lepton mixing from many
different models
Many diff. Processes, e.g. m -> e g
Some processes detector limited, others
beam limited
Polarized muons useful to reduce
backgrounds and discriminate models
produce e.g. by pion decay at rest +
change spin by crossing field
Many beam requirements: intensity, pulsed
or continuous beam (dep. on process), low
pion contamination, narrow energy spread
Jan. 24+25, 2006
ISS KEK Summary - Walter Winter
Current proton drivers:
108 muons/s
(MEG)
few MW PD:
1011-12 muons/s
(PRISM)
NF Frontend:
1014 muons/s
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(Kanemura)
LFV in DIS processes
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Motivation: E. g. Slepton
mixing (SUSY) introduces
LFV at one loop
t-associated LFV
interesting for Higgs-boson
mediated processes
Use DIS process:
e.g. m N -> t X
at neutrino factory
O(102) events for 50 GeV
Also possible: neutrino beam?
Cross section increases with energy!
Therefore: argument for as large Em as possible
Problem: Misidentification of events/Backgrounds;
MC in progress
Jan. 24+25, 2006
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Phenomenology (+ some Theory)
… of neutrino oscillations
Non-accelerator neutrino property measurements
 Non-standard physics
Is there anything else beyond three-flavor
oscillations?
What possible mechanisms?
How does one test those?
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Prospects on n properties
(Choubey)
… from non-accelerator sources
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Dm212 from KamLAND;
but wrong baseline for q12
New reactor experiment?
Gadolinium-loaded SK for
solar parameters?
Atmospheric parameters:
Large magn. iron detector?
Precision comparable to LBL;
Also: Deviations from
maximal mixing, octant
degeneracy
Jan. 24+25, 2006
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(Xing)
Unitarity triangles for lepton sector
Similar to quark sector: Use unitarity triangles
 In see-saw mechanism: 6x6-Matrix unitary;
in all realistic scenarios: active mixing unitary
 Matter effects change unitarity triangles
 Example: Higher E
makes sides comparable;
 Easier to calculate area
 Easier to establish CP viol.
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Jan. 24+25, 2006
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(Sorel)
Status of 3+2 scheme
Can accommodate all data
 Implies: Too low BG for
superbeams, wrong near
detector non-osc. assumption
 Eventually checked by MiniBOONE !?
 If confirmed: Some new interesting physics: Two
new very similar osc. Frequencies introduced; CP
violation by different phases?
Then probably new SBL experiment needed …
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Jan. 24+25, 2006
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(Sato)
Lepton flavor violation?
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May appear in production, propagation, or detection
Describe produced
state by flavor
mixture
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Shift of
matter effect
Describe detected
state by flavor
mixture (simplified)
Neutrinos propagate “off-shell”
Interference effects if same
in/out states
Strong correlations between osc.
and new physics parameters
Different for different types of exp
Models shown: MSSM penguins …
Jan. 24+25, 2006
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Physics with a superbeam, beta beam,
neutrino factory
T2KK
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(Kajita)
Idea: “Double Chooz”
of superbeams?
In addition: Stronger
CP phase dependence +
matter effects
at longer baseline
 10% systematics hardly
problem anymore …
 Substantially improved mass hierarchy reach
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Jan. 24+25, 2006
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(Couce)
Facilities using a Water Cherenkov detector
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Principle advantage of beta
beam: No intrinsic beam BG
New efficiency and
BG matrices for migration
High gamma beta beam
best alternative (even “low flux”)
Jan. 24+25, 2006
Two
different
options!
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Better neutrino factory detector?
(Winter)
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q13 sensitivity
Better detector threshold
makes L=2000-3000 km
very efficient q13-baseline
for exclusion limit
“Magic
baseline”
Mass hier., CP violation
All of the following help:
– Better threshold (especially)
– Better energy resolution
– Smaller matter density
uncertainty (for large q13)
Jan. 24+25, 2006
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Towards the final product:
Performance indicators
and presentation of results?
Performance indicators
Many, many in circulation
 Need to be identical to compare results
 Matter of
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–
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Definition
Tested hypothesis
Purpose
Taste
Computation power
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Example: q13 performance indicators
 q13 exclusion limit (sensitivity
 Describes the new q13 limit for the
hyopthesis of no signal (q13=0)
 Correspond to new limit after the
experiment has been (unsuccessfully)
performed
 q13
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limit):
discovery reach:
Describes if q13=0 can be excluded
for the hypothesis of a certain set
of parameters (q13>0)
Jan. 24+25, 2006
CP fraction plots often used for
discovery potentials!
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Example: dCP-performance indicators
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Purpose:
Looks like result
Purpose:
Risk minimization
Which one(s) useful for ISS study?
True values:
Complete relevant space
– Allowed region in d-q13-plane
Identify how much parameter space remains for specific
hypotheses of true values
– Sensitivity to max. CP violation p/2 or 3p/2
Can CP violation be detected for the hypothesis of max.
CP violation?
– Sensitivity to “any” CP violation
For what fraction of CP violating values can CP
violation be detected? (CP fraction plots)!
– Precision of d ?
How precisely can one measure d? (only defined in the
high precision limit, since d cyclic; also: not Gaussian!)
– CP coverage
How precisely can one measure d or what fraction of the
parameter space can be excluded?
True values:
Few examples
Examples
Level of condensation, computation time
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Towards the presentation of results:
Build strong physics case!
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Main objectives?
– Find q13
– Establish mass hierarchy
– Search for leptonic CP violation
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Theory needed:
Why are these parameters
interesting at all?
Important physics limits:
Jan. 24+25, 2006
ISS KEK Summary - Walter Winter
(Fig. from Huber, Lindner, Winter,
hep-ph/0412199)
– q13 large?
Neutrino factory physics case?
Or vice verse: Only if q13 small?
Better detector key component?
– Physics for q13 zero?
Such as by some symmetry …
May be important for funding
agencies!
E. g. mass hierarchy, MSW effect…
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More physics can be done!
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Include other possible physics;
qualitatively or quantitatively? How?
Examples:
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–
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Certainly good
theoretical motivation,
e.g., quark-leptoncomplementarity, mass
models etc.
Measure q13 precisely as soon as found
Measure dCP precisely as soon as found
Measure leading atmospheric parameters
Deviations from maximal atmospheric mixing
Resolution of octant degeneracy
Test unitarity
New physics ad-mixtures?
MSW effect sensitivity
Matter density measurements?
…
Jan. 24+25, 2006
ISS KEK Summary - Walter Winter
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Example: Optimization for large q13
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Mass hierarchy no
problem for L >>
1000 km
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CP fraction for
CP violation (3s):
“Standard”
“Optimal
appearance”
L=1000 km/Em=20 GeV
possible alternative?
(Huber, Lindner, Rolinec, Winter, to appear)
Jan. 24+25, 2006
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Example: New physics tests
How can this be done by “simple” experimental strategies?
Theory/Phenomenology:
Link specific models (e.g. LFV) with general tests?
Or: Just wait until some inconsistency discovered?
See many talks in
Examples:
1. nt detection Pee+Pem+Pet = 1?
Requires action! (“Wait and see” does not work here …)
this workshop for
specific possible effects!
E.g. Hisano, Kanemura,
Sato, Sorel, Xing
3.
Neutral currents (hard, but maybe competitive to 1. ?)
Spectral signature from effects on probability level
4.
More complicated: Hamiltonian-level effects (LFV etc.)
2.
(decay, …)
Advantage: Characteristic depletion/enhancement in certain regions of
spectrum, oscillation nodes not shifted
Problem: Shifts oscillation nodes, confusion with “standard” parameters
Note: At least 1. and 2. sufficient but not necessary for new physics!
Jan. 24+25, 2006
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Some biased conceptualities …
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How to present multiple options, such as for detector
etc?
– Avoid too many options mixed up (confusing)
– Discuss different options in one section and
choose one “representative” for main line
of argumentation?
– Need that representative asap if September goal!!!
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Problem: Computation time for more complex
calculations: GLoBES on parallel cluster!
So far: used mainly opportunistic systems
At the end: Very small number of meaningful key
figures required
Jan. 24+25, 2006
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Open questions
Physics – Detector
Physics – Accelerator
Detector – (Physics) – Accelerator
Open questions: Physics-Detector
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Ken Long: “close loop”
Need now best possible detector
concept (such as in glb-files) with
1. Better low energy efficiences
2. Better energy resolution?
Can be either one detector or hybrid technology
(same site)
Better detector = key component in large q13
discussion!?
In addition: ne detection, silver channel concepts +
Relevance for physics, optimization, baselines
Jan. 24+25, 2006
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Open questions: Physics-Accelerator
Physics: What muon energy really required?
 Acc.: How much would that reduce the effort?
 Example: 40 GeV for q13, dCP, mass hier.:
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Physics: How large can flux uncertainty be? (Scott Berg)
Jan. 24+25, 2006
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Storage ring+possible NF program?
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m+
m-
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m+
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silver
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m-
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MB
t=0 yr: Start with one baseline,
two polarities, “golden channel”, L=3,000 km
Em = 20 GeV, mD=50kt, 2 MW proton driver?
t=3 yr: First data analysis
Problem: not in fortunate region in param. space
Decision: Go to “magic” baseline + silver channel
after five more years of data taking
t=5 yr: Upgrade, still at L=3,000 km
Em = 40 GeV, mD=100kt, 4 MW proton driver
t=8 yr: Stop data taking; connect new storage ring
t=10 yr: Start at “magic” baseline+silver channel (new
baseline) with one polarity (neutrino appearance only)
t=13 yr: Data analysis: Signal! Start precision measurement
t=15 yr: Decide to change polarity
t=20 yr: End of program
Flexible storage ring concept? Physics: How many baselines?
Jan. 24+25, 2006
ISS KEK Summary - Walter Winter
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Open questions: Detector-Accelerator
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(maybe not our business …)
3s sensitivity to sin22q13
Better Eres
Better threshold
Better Eres+thresh.
(Huber, Lindner, Rolinec, Winter, to appear)
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Optimization: Better detector versus higher muon energy?
Jan. 24+25, 2006
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Next steps: Goals for Boston
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Conceptual cases? Link to theory?
Examples:
– Large q13: sin22q13 > 0.01
(Physics case for NuFact at all? vs. Superbeams?)
– Small q13: 10-4 < sin22q13 < 10-1
(NuFact’s “golden age”?)
– “Zero” q13: sin22q13 << 10-4
(What physics can be done? What does that mean?)
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How to deal with a positive MiniBOONE signal?
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How many baselines needed?
Channel requirements, optimization, …
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Disaster or “golden age” of neutrino physics?
Last-minute changes or matter of argumentation?
How to conceptualize “new physics” tests and post-MiniBOONE physics?
Jan. 24+25, 2006
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Summary
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Theory/phenomenology: very rich information
collected from many different sources
Next steps: How to conceptualize/order that?
General approaches to new physics tests?
Experiment simulations and muons:
– Partly work in progress (superbeams, beta beams, etc.)
– But: At this put input from detector (+accelerator) WG
required (best to come up with)
– Some open questions (such as channel requirements)
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Next steps: Concept! Work on physics cases ...
Think about “final product” …
Jan. 24+25, 2006
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