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Physics working group summary. 2 nd ISS Meeting KEK, Tsukuba, Japan January 23-25, 2006 Walter Winter Institute for Advanced Study, Princeton For the ISS physics working group. Contents. Introduction Meeting summary: Theory (… and muon physics)

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Physics working group summary

Physics working group summary

2nd ISS MeetingKEK, Tsukuba, JapanJanuary 23-25, 2006

Walter Winter

Institute for Advanced Study, Princeton

For the ISS physics working group


  • Introduction

  • Meeting summary:

    • Theory (… and muon physics)

    • Phenomenology: Non-accelerator measurements and “new physics”

    • Physics with a superbeam, beta beam, neutrino factory

  • Towards the final product:Performance indicators and presentation of results?

  • Open questions, next steps

  • Summary

ISS KEK Summary - Walter Winter

Three flavor oscillations requirements
Three-flavor oscillations: Requirements

Atmosphericoscillation:Amplitude: q23Frequency: Dm312

Solaroscillation:Amplitude: q12Frequency: Dm212

Sub-leading effect: dCP

Coupling strength: q13

Key to subleadingeffects (CP violation, mass hierarchy)

  • Neutrino oscillation parameters (1s):Dm212 ~ 8.2 10-5 eV2 +- 5%sin22q12 ~ 0.83 +- 5%|Dm312| ~ (2 – 2.5) 10-3 eV2sin22q23 ~ 1 +- 7%sin22q13 < 0.14dCP = ?Mass hierarchy?

(see e.g. Bahcall et al, hep-ph/0406294; Super-K, hep-ex/0501064; CHOOZ+solar papers)

Superbeam/n-factory/Beta Beam

ISS KEK Summary - Walter Winter

Theory plus some muon physics

Theory(plus some muon physics)

Why are the parameters, which we want to study, interesting at all?

(more specific versions of “big questions”)


Flavor symmetry
Flavor symmetry?


Same gauge quantum numbers, but mass hierarchy and small mixings “unnatural” (for quarks, charged leptons)

  • 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?

Symmetry“Flavor symmetry”

Emmy Noether

Conserved quantityHidden quantum number

ISS KEK Summary - Walter Winter

Quark lepton complementarity


Quark-Lepton complementarity?

  • Understand phenomenological relationships between quarks and leptons at deeper level

  • Example:

  • Deeper underlying reason or accidental?

  • Note: CKM/MNSmatrix is compositedof two parts

  • Implement QLC?

    Important in future:

    parameter precision measurements!

ISS KEK Summary - Walter Winter

Massive neutrinos in cosmology


Massive neutrinos in cosmology

  • 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!

ISS KEK Summary - Walter Winter

Flavor physics to establish susy


Flavor physics to establish SUSY?

  • 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

ISS KEK Summary - Walter Winter

Towards search for charged lepton mixing at nufact


(Towards) search for charged lepton mixing at NuFact

Current proton drivers: 108 muons/s(MEG)

  • Charged lepton mixing from manydifferent models

  • Many diff. Processes, e.g. m -> e gSome processes detector limited, others beam limited

  • Polarized muons useful to reduce backgrounds and discriminate modelsproduce 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

4 MW PD: 1011-12 muons/s(PRISM)

NF Frontend: 1014 muons/s

ISS KEK Summary - Walter Winter

Lfv in dis processes


LFV in DIS processes

  • Motivation: E. g. Sleptonmixing (SUSY) introduces LFV at one loop

  • t-associated LFVinteresting for Higgs-boson mediated processes

  • Use DIS process: e.g. m N -> t X at neutrino factoryO(102) events for 50 GeVAlso possible: neutrino beam?

  • Cross section increases with energy!Therefore: argument for as large Em as possible

  • Problem: Misidentification of events/Backgrounds; MC in progress

ISS KEK Summary - Walter Winter

Phenomenology some theory of neutrino oscillations

Phenomenology (+ some Theory)… of neutrino oscillations

Non-accelerator neutrino property measurements

Non-standard physicsIs there anything else beyond three-flavor oscillations?What possible mechanisms?How does one test those?

Prospects on n properties from non accelerator sources
Prospects on n properties… from non-accelerator sources


  • Dm212 from KamLAND;but wrong baseline for q12New 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

ISS KEK Summary - Walter Winter

Unitarity triangles for lepton sector


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 Emakes sides comparable;

  • Easier to calculate area

  • Easier to establish CP viol.

ISS KEK Summary - Walter Winter

Status of 3 2 scheme


Status of 3+2 scheme

  • Can accommodate all data

  • Implies: Too low BG forsuperbeams, 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 …

ISS KEK Summary - Walter Winter

Lepton flavor violation


Lepton flavor violation?

  • May appear in production, propagation, or detection

  • 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 …

Describe produced state by flavor mixture

Describe detected state by flavor mixture (simplified)

Shift of matter effect

ISS KEK Summary - Walter Winter



  • Idea: “Double Chooz” of superbeams?

  • In addition: StrongerCP phase dependence +matter effectsat longer baseline

  • 10% systematics hardlyproblem anymore …

  • Substantially improved mass hierarchy reach

ISS KEK Summary - Walter Winter

Facilities using a water cherenkov detector


Facilities using a Water Cherenkov detector

  • Principle advantage of betabeam: No intrinsic beam BG

  • New efficiency andBG matrices for migration

  • High gamma beta beambest alternative (even “low flux”)

Two differentoptions!

ISS KEK Summary - Walter Winter

Better neutrino factory detector


Better neutrino factory detector?


  • q13 sensitivityBetter detector threshold makes L=2000-3000 km very efficient q13-baseline for exclusion limit

  • Mass hier., CP violationAll of the following help:

    • Better threshold (especially)

    • Better energy resolution

    • Smaller matter density uncertainty (for large q13)

ISS KEK Summary - Walter Winter

Towards the final product performance indicators and presentation of results

Towards the final product:Performance indicators and presentation of results?

Performance indicators
Performance indicators

  • Many, many in circulation

  • Need to be identical to compare results

  • Matter of

    • Definition

    • Tested hypothesis

    • Purpose

    • Taste

    • Computation power

ISS KEK Summary - Walter Winter

E xample q 13 performance indicators
Example: q13 performance indicators

  • q13 exclusion limit (sensitivity limit):

  • 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 discovery reach:

  • Describes if q13=0 can be excluded for the hypothesis of a certain set of parameters (q13>0)

CP fraction plots often used for discovery potentials!

ISS KEK Summary - Walter Winter

Example d cp performance indicators
Example: dCP-performance indicators

  • Examples

    • Allowed region in d-q13-planeIdentify how much parameter space remains for specific hypotheses of true values

    • Sensitivity to max. CP violation p/2 or 3p/2Can CP violation be detected for the hypothesis of max. CP violation?

    • Sensitivity to “any” CP violationFor 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 coverageHow precisely can one measure d or what fraction of the parameter space can be excluded?

      Which one(s) useful for ISS study?

True values: Few examples

Purpose: Looks like result

Level of condensation, computation time

Purpose: Risk minimization

True values: Complete relevant space

ISS KEK Summary - Walter Winter

Towards the presentation of results build strong physics case
Towards the presentation of results:Build strong physics case!

Theory needed:Why are these parametersinteresting at all?

  • Main objectives?

    • Find q13

    • Establish mass hierarchy

    • Search for leptonic CP violation

  • Important physics limits:

    • 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 fundingagencies!E. g. mass hierarchy, MSW effect…

(Fig. from Huber, Lindner, Winter, hep-ph/0412199)

ISS KEK Summary - Walter Winter

More physics can be done
More physics can be done!

  • Include other possible physics;qualitatively or quantitatively? How?

  • Examples:

    • 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?

Certainly goodtheoretical motivation,e.g., quark-lepton-complementarity, massmodels etc.

ISS KEK Summary - Walter Winter

Example optimization for large q 13
Example: Optimization for large q13

  • Mass hierarchy no problem for L >> 1000 km

  • CP fraction for CP violation (3s):“Standard”“Optimal appearance”L=1000 km/Em=20 GeVpossible alternative?


(Huber, Lindner, Rolinec, Winter, to appear)

ISS KEK Summary - Walter Winter

Example new physics tests
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?


  • nt detection Pee+Pem+Pet = 1? Requires action! (“Wait and see” does not work here …)

  • Neutral currents (hard, but maybe competitive to 1. ?)

  • Spectral signature from effects on probability level (decay, …)Advantage: Characteristic depletion/enhancement in certain regions ofspectrum, oscillation nodes not shifted

  • More complicated: Hamiltonian-level effects (LFV etc.)Problem: Shifts oscillation nodes, confusion with “standard” parameters

    Note: At least 1. and 2. sufficient but not necessary for new physics!

See many talks inthis workshop forspecific possible effects!E.g. Hisano, Kanemura, Sato, Sorel, Xing

ISS KEK Summary - Walter Winter

Some biased conceptualities
Some biased conceptualities …

  • How to present multiple options, such as for detector etc?

    • Avoid too many options mixed up (confusing)

    • Discuss different options in one section andchoose one “representative” for main lineof argumentation?

    • Need that representative asap if September goal!!!

  • 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

ISS KEK Summary - Walter Winter

Open questions

Open questions

Physics – Detector

Physics – Accelerator

Detector – (Physics) – Accelerator

Open questions physics detector
Open questions: Physics-Detector

  • Ken Long: “close loop”Need now best possible detector concept (such as in glb-files) with 1. Better low energy efficiences2. 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

ISS KEK Summary - Walter Winter

Open questions physics accelerator
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.:

  • Physics: How large can flux uncertainty be? (Scott Berg)

ISS KEK Summary - Walter Winter

Storage ring possible nf program





Storage ring+possible NF program?

  • 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 analysisProblem: not in fortunate region in param. spaceDecision: 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?


ISS KEK Summary - Walter Winter

Open questions detector accelerator maybe not our business
Open questions: Detector-Accelerator(maybe not our business …)

  • 3s sensitivity to sin22q13

  • Optimization: Better detector versus higher muon energy?

Better Eres

Better threshold

Better Eres+thresh.


(Huber, Lindner, Rolinec, Winter, to appear)

ISS KEK Summary - Walter Winter

Next steps goals for boston
Next steps: Goals for Boston

  • 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?)

  • How to deal with a positive MiniBOONE signal? Disaster or “golden age” of neutrino physics?Last-minute changes or matter of argumentation?How to conceptualize “new physics” tests and post-MiniBOONE physics?

  • How many baselines needed?

  • Channel requirements, optimization, …

ISS KEK Summary - Walter Winter


  • 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)

  • Next steps: Concept! Work on physics cases ... Think about “final product” …

ISS KEK Summary - Walter Winter