Near detectors for new physics searches

1. Near detectors for new physics searches IDS-NF plenary meeting at TIFR, Mumbai October 12, 2009Walter Winter Universität Würzburg TexPoint fonts used in EMF: AAAAAAAA

2. 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)

3. Near detectors for standard oscillation physics • Need two near detectors, because m+/m- 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)

4. See my talk tomorrow! 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 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!

5. 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)

6. 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

7. 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.!

8. 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!

9. 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“?

10. 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)

11. 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)

12. 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 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 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)

13. 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

14. 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!

15. 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)

16. 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)

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

18. 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

19. 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/