Oscillations Beyond Three-Neutrino Mixing (Status of Light Sterile Neutrinos) Carlo Giunti

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1 C. Giunti Oscillations Beyond Three-Neutrino Mixing Moriond EW 07 4 March 07 /3 Oscillations Beyond Three-Neutrino Mixing (Status of Light Sterile Neutrinos) Carlo Giunti INFN, Torino, Italy Moriond Electroweak Interactions and Unified Theories 07 La Thuile, Aosta Valley, Italy, 8-5 March 07

2 Indications of SBL Oscillations Beyond 3ν C. Giunti Oscillations Beyond Three-Neutrino Mixing Moriond EW 07 4 March 07 /3

3 C. Giunti Oscillations Beyond Three-Neutrino Mixing Moriond EW 07 4 March 07 3/3 LSND [PRL 75 (995) 650; PRC 54 (996) 685; PRL 77 (996) 308; PRD 64 (00) 07] ν µ ν e 0 MeV E 5.8 MeV Well-known and pure source of ν µ p target π at rest µ ν µ µ at rest e ν e ν µ ν e p n e Well-known detection process of ν e 3.8σ excess L 30 m But signal not seen by KARMEN at L 8 m with the same method [PRD 65 (00) 0]

4 C. Giunti Oscillations Beyond Three-Neutrino Mixing Moriond EW 07 4 March 07 4/3 m (ev /c 4 ) Karmen Bugey CCFR NOMAD % (L max -L <.3) 99% (L max -L < 4.6) sin θ m SBL 3 ev m ATM.5 3 ev m SOL

MeV E 3 GeV ν µ ν e [PRL (03) 680] LSND signal LSND signal

Similar L/E (oscillations). No money, no Near Detector.

5 C. Giunti Oscillations Beyond Three-Neutrino Mixing Moriond EW 07 4 March 07 5/3 MiniBooNE L 54 m ν µ ν e [PRL (009) 80] 00 MeV E 3 GeV ν µ ν e [PRL (03) 680] LSND signal LSND signal Purpose: check LSND signal. Different L and E. Similar L/E (oscillations). No money, no Near Detector. LSND signal: E > 475 MeV. Agreement with LSND signal? CP violation? Low-energy anomaly!

6 Gallium Anomaly Gallium Radioactive Source Experiments: GALLEX and SAGE ν e Sources: e 5 Cr 5 V ν e e 37 Ar 37 Cl ν e E 0.75 MeV E 0.8 MeV Test of Solar ν e Detection: ν e 7 Ga 7 Ge e R =N exp N cal GALLEX SAGE Cr Cr R = 0.84 ± 0.05 L GALLEX =.9 m GALLEX SAGE Cr Ar L SAGE = 0.6 m m SBL ev m ATM m SOL.9σ deficit [SAGE, PRC 73 (006) ; PRC 80 (009) 05807; Laveder et al, Nucl.Phys.Proc.Suppl. 68 (007) 344, MPLA (007) 499, PRD 78 (008) , PRC 83 (0) ] C. Giunti Oscillations Beyond Three-Neutrino Mixing Moriond EW 07 4 March 07 6/3

7 Reactor Electron Antineutrino Anomaly C. Giunti Oscillations Beyond Three-Neutrino Mixing Moriond EW 07 4 March 07 7/3 [Mention et al, PRD 83 (0) ] New reactor ν e fluxes [Mueller et al, PRC 83 (0) 05465; Huber, PRC 84 (0) 0467] R = N exp N cal Bugey 3 Bugey 4 Chooz Daya Bay Double Chooz Gosgen ILL Krasnoyarsk Nucifer 3 L [m].5σ deficit Palo Verde RENO Rovno88 R = ± 0.04 Rovno9 SRP

8 C. Giunti Oscillations Beyond Three-Neutrino Mixing Moriond EW 07 4 March 07 8/3 P ν e νe Bugey 4 Rovno9 E 4MeV sin ϑ ee = 0. m 4 = 0. ev m 4 = 0.5 ev m 4 =.0 ev Rovno88 Bugey 3 Gosgen ILL 3 L [m] Krasnoyarsk SRP Nucifer R DC DB DC R DB m SBL 0.5 ev m ATM m SOL

9 ε C. Giunti Oscillations Beyond Three-Neutrino Mixing Moriond EW 07 4 March 07 9/3 NEOS [arxiv:6.0534] Events /day/0 kev Data/Prediction Data/Prediction (a) (b) Prompt Energy [MeV] Data signal (ON-OFF) Data background (OFF) MC 3ν (H-M-V) MC 3ν (Daya Bay) NEOS/H-M-V Systematic total Neutrino Energy [MeV] (c) NEOS/Daya Prompt BayEnergy [MeV] Systematic total.0 (.73 ev, 0.050) (.3 ev, 0.4) Prompt Energy [MeV] 3 Hanbit Nuclear Power Complex in Yeong-gwang, Korea. Thermal power of.8 GW. Detector: a ton of Gd-loaded liquid scintillator in a gallery approximately 4 m from the reactor core. The measured antineutrino event rate is 976 per day with a signal to background ratio of about.

10 C. Giunti Oscillations Beyond Three-Neutrino Mixing Moriond EW 07 4 March 07 /3 ] 4 [ev m RAA allowed 90% CL 95% CL 99% CL NEOS Spectrum 90% CL 95% CL 99% CL Excluded NEOS 90% CL Bugey-3 90% CL Daya Bay 90% CL s [ev ] m 4 sin θ 4 Raster Scan [NEOS, arxiv:6.0534] Best Fits: m4 =.7 ev sin θ 4 = 0.05 m4 =.3 ev sin θ 4 = sin ϑ ee -D χ Analysis χ no osc. χ min = 6.5.σ anomaly

11 Beyond Three-Neutrino Mixing: Sterile Neutrinos C. Giunti Oscillations Beyond Three-Neutrino Mixing Moriond EW 07 4 March 07 /3 m. ν 5. ν s ν 4 m SBL ν s ev ν 3 ν ν matm msol ν e ν µ ν τ.5 3 ev ev Terminology: means: a ev-scale sterile neutrino a ev-scale massive neutrino which is mainly sterile

12 Sterile Neutrinos from Physics Beyond the SM Neutrinos are special in the Standard Model: the only neutral fermions Active left-handed neutrinos can mix with non-sm singlet fermions often called right-handed neutrinos Neutrino Portal [A. Smirnov, arxiv: ] Light left-handed anti-ν R are light sterile neutrinos ν c R ν sl (left-handed) Sterile means no standard model interactions [Pontecorvo, Sov. Phys. JETP 6 (968) 984] Active neutrinos (ν e, ν µ, ν τ ) can oscillate into light sterile neutrinos (ν s ) Observables: Disappearance of active neutrinos (neutral current deficit) Indirect evidence through combined fit of data (current indication) Short-baseline anomalies 3ν-mixing: m m 3 m 4... ν ν ν 3 ν 4... ν e ν µ ν τ ν s... C. Giunti Oscillations Beyond Three-Neutrino Mixing Moriond EW 07 4 March 07 /3

13 C. Giunti Oscillations Beyond Three-Neutrino Mixing Moriond EW 07 4 March 07 3/3 Effective 3 SBL Oscillation Probabilities Appearance (α β) ( ) m P SBL ( ) sin ϑ ν ( ) αβ sin 4 L α ν β 4E Disappearance ( ) m P SBL ( ) sin ϑ ν ( ) αα sin 4 L α ν α 4E sin ϑ αβ = 4 U α4 U β4 sin ϑ αα = 4 U α4 ( U α4 ) U e U e U e3 U e4 U µ U µ U µ3 U µ4 U = U τ U τ U τ3 U τ4 U s U s U s3 U s4 SBL 6 mixing angles 3 Dirac CP phases 3 Majorana CP phases CP violation is not observable in SBL experiments! Observable in LBL accelerator exp. sensitive to matm [de Gouvea et al, PRD 9 (05) , PRD 9 (05) 0730, arxiv: ; Palazzo et al, PRD 9 (05) 07307, PLB 757 (06) 4; Gandhi et al, JHEP 5 (05) 039] and solar exp. sensitive to m SOL [Long, Li, CG, PRD 87, 3004 (03) 3004]

14 C. Giunti Oscillations Beyond Three-Neutrino Mixing Moriond EW 07 4 March 07 4/3 Global ν e and ν e Disappearance [Gariazzo, CG, Laveder, Li, arxiv: ] [ev ] m 4 ν edis σ σ σ Reactors Gallium ν ec Sun TK KARMENLSND ν e C [Conrad, Shaevitz, PRD 85 (0) 0307] [CG, Laveder, PLB 706 (0) 0] Solar ν e KamLAND ν e [Li et al, PRD 80 (009) 3007, PRD 86 (0) 304] [Palazzo, PRD 83 (0) 303, PRD 85 (0) 07730] TK Near Detector ν e disappearance [TK, PRD 9 (05) 05] sin ϑ ee χ NO = σ anomaly Best Fit: m 4 =.7 ev sin ϑ ee = U e4 = 0.07 χ min /NDF = 6.5/74 GoF = 7% χ PG /NDF PG = 3.8/7 GoF PG = 6%

15 C. Giunti Oscillations Beyond Three-Neutrino Mixing Moriond EW 07 4 March 07 5/3 Global ν e and ν e Disappearance β Decay [Gariazzo, CG, Laveder, Li, arxiv: ] ν edisβ σ σ σ ν edis β Best Fit: m 4 =.7 ev sin ϑ ee = U e4 = 0.06 m 4 [ev ] cm Losc 4 8 m at E [MeV] sin ϑ ee 0. at sin ϑ ee

16 C. Giunti Oscillations Beyond Three-Neutrino Mixing Moriond EW 07 4 March 07 6/3 3 The Race for ν e and ν e Disappearance CeSOX shape (95% CL) CeSOX rate (95% CL) CeSOX rateshape (95% CL) BEST (σ) IsoDAR@KamLAND (5yr, ) IsoDAR@C ADS (5yr, ) KATRIN (90% CL) ν edisβ σ σ 3 DANSS (yr, 95% CL) Neutrino 4 (yr, 95% CL) PROSPECT phase (3yr, ) PROSPECT phase (3yr, ) SoLiD phase (yr, 95% CL) SoLiD phase (3yr, ) STEREO (yr, 95% CL) ν edisβ σ σ [ev ] m 4 [ev ] m sin ϑ ee CeSOX (Gran Sasso, Italy) 44 Ce ν e BOREXINO: L 5-m [Vivier@TAUP05] BEST (Baksan, Russia) 5 Cr ν e L 5-m [PRD 93 (06) 07300] IsoDAR@KamLAND (Kamioka, Japan) 8 Li ν e L 6m [arxiv:5.0530] IsoDAR@C-ADS (Guangdong, China) 8 Li ν e L 5m [JHEP 60 (06) 004] sin ϑ ee DANSS (Kalinin, Russia) L -m [arxiv: ] Neutrino-4 (RIAR, Russia) L 6-m [JETP (05) 578] PROSPECT (ORNL, USA) L 7-m [arxiv:5.00] SoLid (SCK-CEN, Belgium) L 5-8m [arxiv: ] STEREO (ILL, France) L 8-m [arxiv: ] KATRIN (Karlsruhe, Germany) 3 H ν e [Drexlin@NOW06]

17 ν µ ν e and ν µ ν e Appearance 99% CL LSND MiniBooNE KARMEN NOMAD BNL E776 ICARUS OPERA [ev ] m 4 ν µ ν e 90% CL 95% CL 99% CL 3 sin ϑ eµ C. Giunti Oscillations Beyond Three-Neutrino Mixing Moriond EW 07 4 March 07 7/3

18 ν µ and ν µ Disappearance [ev ] m 4 99% CL CDHSW: νµ (984) ATM: νµ νµ SciBooNE MiniBooNE: νµ (0) SciBooNE MiniBooNE: νµ (0) MINOS: νµ CCNC (06) IceCube: νµ νµ (06) sin ϑ µµ C. Giunti Oscillations Beyond Three-Neutrino Mixing Moriond EW 07 4 March 07 8/3

19 3 Appearance-Disappearance Tension ν e DIS sin ϑ ee 4 U e4 ν µ ν e APP ν µ DIS sin ϑ µµ 4 U µ4 sin ϑ eµ = 4 U e4 U µ4 4 sin ϑ ee sin ϑ µµ [Okada, Yasuda, IJMPA (997) 3669; Bilenky, CG, Grimus, EPJC (998) 47] ν µ ν e is quadratically suppressed! [ev ] m 4 PrGlo7 σ σ ν e Dis ν µ Dis Dis App 4 3 PrGlo7 = Pragmatic Global Fit 07 [Gariazzo, CG, Laveder, Li, arxiv: ] χ NO = σ anomaly Best Fit: m4 =.7 ev U e4 = 0.09 U µ4 = 0.05 χ min /NDF = 594.8/579 GoF = 3% χ PG /NDF PG = 7.4/ GoF PG = 3% Similar tension in 3, 33,..., 3N s [CG, Zavanin, MPLA 3 (05) ] sin ϑ eµ C. Giunti Oscillations Beyond Three-Neutrino Mixing Moriond EW 07 4 March 07 9/3

20 C. Giunti Oscillations Beyond Three-Neutrino Mixing Moriond EW 07 4 March 07 0/3 Effects of MINOS, IceCube and NEOS ( ) ν µ ( ) ν µ ( ) ν e ( ) ν e PrGlo6A PrGlo6A MINOS PrGlo6A IceCube PrGlo6A MINOS IceCube = PrGlo6B PrGlo6A PrGlo6A MINOS IceCube = PrGlo6B PrGlo6A MINOS IceCube NEOS = PrGlo7 [ev ] [ev ] m 4 m 4 MINOS IceCube sin ϑ µµ NEOS sin ϑ ee

21 C. Giunti Oscillations Beyond Three-Neutrino Mixing Moriond EW 07 4 March 07 /3 The Race for the Light Sterile ( ) ν e ( ) ν e PrGlo7 σ σ PrGlo7 σ σ [ev ] [ev ] m 4 m 4 DANSS (yr, 95% CL) Neutrino 4 (yr, 95% CL) PROSPECT phase (3yr, ) PROSPECT phase (3yr, ) SoLiD phase (yr, 95% CL) SoLiD phase (3yr, ) STEREO (yr, 95% CL) sin ϑ ee CeSOX shape (95% CL) CeSOX rate (95% CL) CeSOX rateshape (95% CL) BEST (σ) IsoDAR@KamLAND (5yr, ) IsoDAR@C ADS (5yr, ) KATRIN (90% CL) sin ϑ ee

22 C. Giunti Oscillations Beyond Three-Neutrino Mixing Moriond EW 07 4 March 07 /3 ( ) ν µ ( ) ν e ( ) ν µ ( ) ν µ SBN (3yr, ) nuprism () JSNS () SBN (3yr, ) KPipe (3yr, ) [ev ] [ev ] m 4 m 4 PrGlo7 σ σ 4 3 sin ϑ eµ PrGlo7 σ σ sin ϑ µµ

23 C. Giunti Oscillations Beyond Three-Neutrino Mixing Moriond EW 07 4 March 07 3/3 Conclusions Exciting indications of light sterile neutrinos at the ev scale: LSND ν µ ν e signal. Gallium ν e disappearance. Reactor νe disappearance. Vigorous experimental program to check conclusively in a few years: ν e and ν e disappearance with reactors and radioactive sources. ν µ ν e transitions with accelerator neutrinos. ν µ disappearance with accelerator neutrinos. Independent tests through effect of m 4 in β-decay and ββ 0ν -decay. Cosmology: strong tension with N eff = and m 4 ev. It may be solved by a non-standard cosmological mechanism. Possibilities for the next years: Reactor and source experiments νe and ν e observe SBL oscillations: big excitement and explosion of the field. Otherwise: still marginal interest to check the LSND appearance signal. In any case the possibility of the existence of sterile neutrinos related to New Physics beyond the Standard Model will continue to be studied (e.g kev sterile neutrinos).

24 Backup Slides C. Giunti Oscillations Beyond Three-Neutrino Mixing Moriond EW 07 4 March 07 4/3

25 C. Giunti Oscillations Beyond Three-Neutrino Mixing Moriond EW 07 4 March 07 5/3 MiniBooNE Low-Energy Anomaly m 4 [ev ] ν e&ν µdis ATMSUN OPERA MiniBooNE ICARUS ν edis ν µdis 4 3 sin ϑ eµ * Excess Events / MeV E MiniBooNE ν e Data Expected Background sin ϑ =.00, m = 0.04 ev (bf) sin ϑ = 0.007, m = 0.5 ev sin ϑ = 0.00, m = 0.9 ev sin ϑ = 0.003, m = 3 ev [MeV] No fit of low-energy excess for realistic sin ϑ eµ 3 3

26 C. Giunti Oscillations Beyond Three-Neutrino Mixing Moriond EW 07 4 March 07 6/3 ( ) ν µ ( ) ν e ( ) ν e ( ) ν e ( ) ν µ ( ) ν µ [ev ] [ev ] [ev ] m 4 m 4 m 4 Glo6A Glo6B Glo7 PrGlo7 3 sin ϑ eµ Glo6A Glo6B Glo7 PrGlo7 sin ϑ ee Glo6A Glo6B Glo7 PrGlo7 sin ϑ µµ

Another Analysis of SBL IceCube C. Giunti Oscillations Beyond Three-Neutrino Mixing Moriond EW 07 4 March 07 7/3 [Collin, Arguelles, Conrad, Shaevitz, PRL 7 (06) 80 (arxiv:607.

27 Another Analysis of SBL IceCube C. Giunti Oscillations Beyond Three-Neutrino Mixing Moriond EW 07 4 March 07 7/3 [Collin, Arguelles, Conrad, Shaevitz, PRL 7 (06) 80 (arxiv: )] SBL SBL IceCube Red: 90% CL Blue: 99% CL 3 m 4 U e4 U µ4 U τ4 N bins χ min χ null χ (dof) SBL (3) SBLIC (4) IC ()

28 Bounds on U τ4 ev m 4 0 MINOS atm MB disapp CDHS worst phases MINOS best phases τ4 U worst phases best phases [Kopp et al, JHEP 305 (03) 050] U µ4 [Super-Kamiokande, PRD 9 (05) 0509] 4 (ev ) m LLH % C.L. 90% C.L. SK (05), 90 % C.L. SK (05), 99 % C.L. IceCube (06), 90 % C.L. 90% C.L. 99% C.L % CL OPERA NH OPERA IH CHORUS NOMAD Uτ4 = sin θ34 cos θ IceCube (06), 99 % C.L sin θ µτ ν µ ν τ [OPERA, JHEP 506 (05) 069] Uµ4 = sin θ LLH [IceCube DeepCore, arxiv: ] C. Giunti Oscillations Beyond Three-Neutrino Mixing Moriond EW 07 4 March 07 8/3

29 [Collin et al, PRL 7 (06) 80] 90% CL ϑ 34 < 6 for m 4 6 ev ϑ 34 < 80 for m 4 ev χ [Gariazzo, CG, Laveder, Li, arxiv: ] Glo6B Glo7 PrGlo7 U τ % CL 99% CL 95.45% CL 90% CL 68.7% CL 3 90% CL Glo6A MINOS: Glo6A IceCube: Glo6B: Glo7: PrGlo7: ϑ 34 < 7 ϑ 34 < 7.3 ϑ 34 < 7.3 ϑ 34 < 5.6 ϑ 34 < 6.0 C. Giunti Oscillations Beyond Three-Neutrino Mixing Moriond EW 07 4 March 07 9/3

Sterile Neutrinos. Carlo Giunti

Sterile Neutrinos. Carlo Giunti C. Giunti Sterile Neutrinos PPC07 6 May 07 /5 Sterile Neutrinos Carlo Giunti INFN, Torino, Italy XI International Conference on Interconnections between Particle Physics and Cosmology Corpus Christi, Texas,