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Testing neutrino properties at the Neutrino Factory

Testing neutrino properties at the Neutrino Factory. Astroparticle seminar INFN Torino December 3, 2009 Walter Winter Universität Würzburg. TexPoint fonts used in EMF: A A A A A A A A. Contents. The most prominent “neutrino” property: leptonic CP violation (CPV) CPV Phenomenology

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Testing neutrino properties at the Neutrino Factory

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  1. Testing neutrino properties at the Neutrino Factory Astroparticle seminar INFN Torino December 3, 2009Walter Winter Universität Würzburg TexPoint fonts used in EMF: AAAAAAAA

  2. Contents • The most prominent “neutrino” property: leptonic CP violation (CPV) • CPV Phenomenology • Neutrino factory experiment • Near detectors at the Neutrino Factory • New physics searches with near detectors • Summary

  3. CPV: Motivation from theory

  4. Where does CPV enter? • Example: Type I seesaw (heavy SM singlets Nc) Could also be type-II, III seesaw,radiative generation of neutrino mass, etc. Block-diag. Primary source of CPV(depends BSM theory) Charged leptonmass terms Eff. neutrinomass terms Effective source of CPV(only sectorial origin relevant) Observable CPV(completely model-indep.) CC

  5. Connection to measurement • 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 Requires q13 > 0 LBL accessible CPV: dIf  UPMNS real CP conserved CPV in 0nbb decay Extremely difficult! (Pascoli, Petcov, Rodejohann, hep-ph/0209059) There is no specific connectionbetween low- and high-E CPV! But: that‘s not true for special (restrictive) assumptions!

  6. Why is CPV interesting? • Leptogenesis:CPV from Ncdecays • If special assumptions(such as hier. MR, NH light neutrinos, …)it is possible that dCP is the only source of CPV for leptogensis! • If CPV discovery: It is possible to write down a model, in which the baryon asymmetry comes from dCP only (Nc)i (Nc)i ~ MD(in basis where Ml and MR diagonal) Different curves:different assumptions for q13, … (Pascoli, Petcov, Riotto, hep-ph/0611338)

  7. 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(qC) ~ 13 • Can also be seen in sum rules for certain assumptions, such as(F: model parameter) • This talk: Want Cabibbo-angle order precision for dCP! (arXiv:0709.2163) (Niehage, Winter, arXiv:0804.1546)

  8. CPV phenomenology

  9. Terminology • Any value of dCP(except for 0 and p)violates CP • Sensitivity to CPV:Exclude CP-conservingsolutions 0 and pfor any choiceof the other oscillationparameters in their allowed ranges

  10. Measurement of CPV • Antineutrinos: • Magic baseline: • Silver: • Platinum, Superb.: (Cervera et al. 2000; Freund, Huber, Lindner, 2000; Huber, Winter, 2003; Akhmedov et al, 2004)

  11. Degeneracies Iso-probability curves • CP asymmetry(vacuum) suggests the use of neutrinos and antineutrinos • One discrete deg.remains in (q13,d)-plane(Burguet-Castell et al, 2001) • Additional degeneracies: (Barger, Marfatia, Whisnant, 2001) • Sign-degeneracy (Minakata, Nunokawa, 2001) • Octant degeneracy (Fogli, Lisi, 1996) Neutrinos Antineutrinos Best-fit

  12. Intrinsic vs. extrinsic CPV • The dilemma: Strong matter effects (high E, long L), but Earth matter violates CP • Intrinsic CPV (dCP) has to be disentangled from extrinsicCPV (from matter effects) • Example: p-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 Critical range True dCP (violates CP maximally) NuFact, L=3000 km Degeneracy above 2s(excluded) Fit True (Huber, Lindner, Winter, hep-ph/0204352)

  13. The magic baseline

  14. CPV discovery reach … in (true) sin22q13 and dCP Best performanceclose to max. CPV (dCP = p/2 or 3p/2) Sensitive region as a function of trueq13 anddCP dCP values now stacked for each q13 No CPV discovery ifdCP too close to 0 or p No CPV discovery forall values of dCP 3s ~ Cabibbo-angleprecision at 2sBENCHMARK! Read: If sin22q13=10-3, we expect a discovery for 80% of all values of dCP

  15. Next generation reach • Includes Double Chooz, Daya Bay, T2K, NOvA 90% CL (Huber, Lindner, Schwetz, Winter, arXiv:0907.1896)

  16. Beyond the next generationExample: Neutrino factory

  17. Neutrino factory:International design study (Geer, 1997; de Rujula, Gavela, Hernandez, 1998; Cervera et al, 2000) 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 „Euronus“ proposal within the FP 07 • In the US: „Muon collider task force“ Signal prop. sin22q13 Contamination Muons decay in straight sections of a storage ring ISS

  18. IDS-NF baseline setup 1.0 • Two decay rings • Em=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/)

  19. NF physics potential • Excellent q13, 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)

  20. Steve Geer‘s vision

  21. Neutrino factory in stages? • Phase I: Five years low-E NuFact, TASD@900km • Phase II: 5 yr, energy upgrade 25 GeV, MIND@4000km • Phase III: 5 yr, second baseline MIND@7500 km • Example: q13 not found (Tang, Winter, arXiv:0911.5052)

  22. Near detectors at the Neutrino Factory

  23. Near detectors for standard oscillation physics • Need two near detectors, because m+/m- circulate in different directions • For cross section measurements, no CID required, only excellent flavor-ID • Possible locations: (Tang, Winter, arXiv:0903.3039)

  24. Requirementsfor standard oscillation physics (summary) • Muon neutrino+antineutrino inclusive CC event rates measured (other flavors not needed in far detectors for IDS-NF baseline) • Charge identification to understand backgrounds (but no intrinsic beam contamination), no ne,nt • 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!

  25. Beam+straight geometry • Near detectors described in GLoBES by e(E)=Aeff/Adet x on-axis flux and • For e(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)

  26. New physics searches with near detectors

  27. New physics from heavy mediators • Effective operator picture if mediators integrated out:Describes additions to the SM in a gauge-inv. way! • Example: TeV-scale new physicsd=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) n mass d=6, 8, 10, ...: NSI, NU

  28. Example 1: Non-standard interactions • Typically described by effective four fermion interactions (here with leptons) • May lead to matter NSI (for g=d=e) • May also lead to source/detector NSI(e.g. NuFact: embs for a=d=e, g=m) These source/det.NSI are process-dep.!

  29. Lepton flavor violation… and the story of SU(2) gauge invariance • Strongbounds Ex.: NSI(FCNC) 4n-NSI(FCNC) CLFV e m ne nm ne nm ne ne e e e e • Affects neutrino oscillations in matter (or neutrino production) • Affects environments with high n 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!

  30. Systematic analysis for d=8 Feynman diagrams Basis (Berezhiani, Rossi, 2001) • Decompose all d=8 leptonic operators systematically (tree level) • The 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) Avoid CLFVat d=8:C1LEH=C3LEH Combinedifferentbasis elements C1LEH, C3LEH Canceld=8CLFV But these mediators cause d=6 effects Additional cancellation condition(Buchmüller/Wyler – basis)

  31. 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  e ~ (v/L)4 ~ 10-4 natural? • „NSI hierarchy problem“?

  32. Source NSI with nt at a NuFact • Probably most interesting for near detectors: eets, emts (no intrinsic beam BG) • Near detectors measure zero-distance effect ~ |es|2 • Helps to resolve correlations 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) ND5: OPERA-like ND at d=1 km, 90% CL (Tang, Winter, arXiv:0903.3039)

  33. Other types of source NSI • In particular models, also other source NSI (without nt detection) are interesting • Example: (incoh.)eems from addl.Higgs triplet asseesaw (II) mediator 1 kt, 90% CL, perfect CID Geometric effects? Effects of std. oscillations Systematics(CID) limitation?CID important! Requires CID! (Malinsky, Ohlsson, Zhang, arXiv:0811.3346)

  34. also: „MUV“ Example 2:Non-unitarity of mixing matrix • Integrating out heavy fermion fields, one obtains neutrino mass and the d=6 operator (here: fermion singlets) • Re-diagonalizing and re-normalizing the kinetic terms of the neutrinos, one has • This can be described by an effective (non-unitary) mixing matrix e with N=(1+e) U • Similar effect to NSI, but source, detector, and matter NSI are correlated in a particular, fundamental way (i.e., process-independent)

  35. Impact of near detector • Example: (Antusch, Blennow, Fernandez-Martinez, Lopez-Pavon, arXiv:0903.3986) • nt near detector important to detect zero-distance effect • Magnetization not mandatory, size matters Curves: 10kt, 1 kt, 100 t, no ND

  36. NSI versus NU • For a neutrino factory, leptonic NSI and NU may have very similar correlations between source and matter effects, e.g. NU (generic, any exp.) NSI (d=6, no CLFV, NF) • Difficult to disentangle with NuFact alone  SB? NU NSI PRELIMINARY (Meloni, Ohlsson, Winter, Zhang, to appear)

  37. 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: ne 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!

  38. SBL ne disappearance • Averaging over straight important (dashed versus solid curves) • Location matters: Depends on Dm312 • Magnetic field ifinteresting as well Two baseline setup? d=50 m d~2 km (as long as possible) 90% CL, 2 d.o.f.,No systematics, m=200 kg (Giunti, Laveder, Winter, arXiv:0907.5487)

  39. SBL systematics • Systematics similar to reactor experiments:Use two detectors to cancel X-Sec errors 10% shape error arXiv:0907.3145 Also possible with onlytwo ND (if CPT-inv. assumed) (Giunti, Laveder, Winter, arXiv:0907.5487)

  40. CPTV discovery reaches (3s) Dashed curves: without averaging over straight Requires four NDs! (Giunti, Laveder, Winter, arXiv:0907.5487)

  41. Summary of (new) physics requirementsfor near detectors • 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

  42. 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 nt near detector to a superbeam version, see e.g.http://www-off-axis.fnal.gov/MINSIS/Workshop next week in Madrid!

  43. Summary • The Dirac phase dCP is probably the only realistically observable CP phase in the lepton sector • Maybe the only observable CPV evidence for leptogenesis • This and f1, f2: the only completely model-inpendent parameterization of CPV • A neutrino factory could measure that even for extremely small q13 with „Cabbibo-angle precision“ • Near detectors at a neutrino factory are very important for new physics searches, such as • Non-unitarity (heavy neutral fermions) • Non-standard interactions (related to CLFV) • (Light) sterile neutrinos • Requirements most likely driven by new physics searches

  44. BACKUP

  45. 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 NFEven if there is no CPV instandard oscillations, we mayfind CPV!But what are the requirements for a model to predict such large NSI? ~ current bound IDS-NF baseline 1.0 (arXiv:0808.3583) 3s

  46. CPV discovery for large NSI • If both q13 and |eetm| 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, e.g. in MUV(Gonzalez-Garcia et al, hep-ph/0105159; Fernandez-Martinez et al, hep-ph/0703098; Altarelli, Meloni, 0809.1041; Antusch et al, 0903.3986) IDS-NF baseline 1.0 (arXiv:0808.3583)

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