Near detectors for new physics searches

IDS-NF plenary meetingat TIFR, MumbaiOctober 12, 2009

Walter WinterUniversität Würzburg

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Contents

Near detectors for standard osc. physics Three (new) physics examples:

Non-standard interactions Non-unitarity of the mixing matrix Sterile neutrinos

Requirements for new physics searches What we need to understand …

NB: For this talk, „near“ means L << 100 km (no std. osc. effect)

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Near detectors for standard oscillation physics

Need two near detectors, because +/- circulate in different directions

For the same reason: if only standard oscillations, no CID required, only excellent flavor-ID

Possible locations:

(Tang, Winter, arXiv:0903.3039)

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Requirementsfor standard oscillation physics

Muon neutrino+antineutrino inclusive CC event rates measured (other flavors not needed in far detectors for IDS-NF baseline)

No charge identification, no e,

At least same characteristics/quality (energy resolution etc.) as far detectors(a silicon vertex detector or ECC or liquid argon may do much better …)

Location and size not really relevant, because extremely large statistics (maybe size relevant for beam monitoring, background extrapolation)

The specifications of the near detectors may actually be driven by new physics searches!

See my talk tomorrow!

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Beam+straight geometry

Near detectors described in GLoBES by (E)=Aeff/Adet x on-axis flux and

For (E) ~ 1: Far detector limit Example: OPERA-

sized detector at d=1 km:

L > ~1 km: GLoBES std. description valid(with Leff)

(Tang, Winter, arXiv:0903.3039)

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Effective operator picture if mediators integrated out:

Describes additions to the SM in a gauge-inv. way! Example: 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

Interesting dimension six operatorsFermion-mediated Non-unitarity (NU)Scalar or vector mediated Non-standard int. (NSI)

New physics from heavy mediators

mass d=6, 8, 10, ...: NSI, NU

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Example 1:

Non-standard interactions Typically described by effective four

fermion interactions (here with leptons)

May lead to matter NSI (for ==e)

May also lead to source/detector NSI(e.g. NuFact:

s for ==e, =)These source/det.NSI are process-dep.!

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Lepton flavor violation… and the story of SU(2) gauge invariance

Strongbounds

e e

e

NSI(FCNC)

e e

e CLFV e

4-NSI(FCNC)

Ex.:

e e

Affects neutrino oscillations in matter (or neutrino production)

Affects environments with high densities (supernovae)

BUT: These phenomena are connected by SU(2) gauge invariance

Difficult to construct large leptonic matter NSI with d=6 operators (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!

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On current NSI bounds (Source NSI for NuFact)

The bounds for the d=6 (e.g.scalar-mediated) operators are strong (CLFV, Lept. univ., etc.)(Antusch, Baumann, Fernandez-Martinez, arXiv:0807.1003)

The model-independent bounds are much weaker(Biggio, Blennow, Fernandez-Martinez, arXiv:0907.0097)

However: note that here the NSI have to come from d=8 (or loop d=6?) operators ~ (v/)4 ~ 10-4 natural?

„NSI hierarchy problem“?

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Source NSI with at a NuFact

Probably most interesting for near detectors: e

s, s (no intrinsic beam BG)

Near detectors measure zero-distance effect ~ |s|2

Helps to resolve correlations

(Tang, Winter, arXiv:0903.3039)

ND5: OPERA-like ND at d=1 km, 90% CL

This correlation is always present if:- NSI from d=6 operators- No CLFV (Gavela et al,arXiv:0809.3451;see also Schwetz, Ohlsson, Zhang, arXiv:0909.0455 for a particular model)

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Other types of source NSI

In particular models, also other source NSI (without detection) are interesting

Example: (incoh.)

es from addl.

Higgs triplet asseesaw (II) mediator

1 kt, 90% CL, perfect CID

(Malinsky, Ohlsson, Zhang, arXiv:0811.3346)

Requires CID!

Geometric effects? Effects of std.

oscillations

Systematics(CID) limitation?CID important!

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Example 2:

Non-unitarity of mixing matrix Integrating out heavy fermion fields, one obtains neutrino

mass and the d=6 operator (here: fermion singletts)

Re-diagonalizing and re-normalizing the kinetic terms of the neutrinos, one has

This can be described by an effective (non-unitary) mixing matrix with N=(1+) U

Similar effect to NSI, but source, detector, and matter NSI are correlated in a particular, fundamental way (i.e., process-independent)

also: „MUV“

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Impact of near detector

Example: (Antusch, Blennow, Fernandez-Martinez, Lopez-Pavon, arXiv:0903.3986)

near detector important to detect zero-distance effect

Magnetization not mandatory, size matters

Curves: 10kt, 1 kt, 100 t, no ND

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Example 3:

Search for sterile neutrinos

3+n schemes of neutrinos include (light) sterile states The mixing with the active states must be small The effects on different oscillation channels depend on

the model test all possible two-flavor short baseline (SBL) cases, which are standard oscillation-free

Example: e disappearanceSome fits indicate an inconsistency between the neutrino and antineutrino data (see e.g. Giunti, Laveder, arXiv:0902.1992)

NB: Averaging over decay straight not possible! The decays from different sections contribute differently!

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SBL e disappearance

Averaging over straight important (dashed versus solid curves)

Location matters: Depends on m31

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Magnetic field if

interesting as well

(Giunti, Laveder, Winter, arXiv:0907.5487)

90% CL, 2 d.o.f.,No systematics,

m=200 kg

Two baseline setup?

d=50 m

d~2 km(as long as possible)

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SBL systematics

Systematics similar to reactor experiments:Use two detectors to cancel X-Sec errors

(Giunti, Laveder, Winter, arXiv:0907.5487)

10% shape

error

arXiv:0907.3145

Also possible with onlytwo ND (if CPT-inv. assumed)

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CPTV discovery reaches (3)

(Giunti, Laveder, Winter, arXiv:0907.5487)

Dashed curves: without averaging over straight Requires four NDs!

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Summary of (new) physics requirements

Number of sitesAt least two (neutrinos and antineutrinos), for some applications four (systematics cancellation)

Exact baselinesNot relevant for source NSI, NU, important for oscillatory effects (sterile neutrinos etc.)

FlavorsAll flavors should be measured

Charge identificationIs needed for some applications (such as particular source NSI); the sensitivity is limited by the CID capabilities

Energy resolutionProbably of secondary importance (as long as as good as FD); one reason: extension of straight leads already to averaging

Detector sizeIn principle, as large as possible. In practice, limitations by beam geometry or systematics.

Detector geometryAs long (and cylindrical) as possible (active volume)

Aeff < Adet Aeff ~ Adet

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What we need to understand

How long can the baseline be for geometric reasons (maybe: use „alternative locations“)?

What is the impact of systematics (such as X-Sec errors) on new physics parameters

What other kind of potentially interesting physics with oscillatory SBL behavior is there?

How complementary or competitive is a near detector to a superbeam version, see e.g.http://www-off-axis.fnal.gov/MINSIS/