Sterile Neutrinos. Carlo Giunti

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1 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, USA, -6 May 07

2 Indications of SBL Oscillations Beyond 3ν C. Giunti Sterile Neutrinos PPC07 6 May 07 /5

3 C. Giunti Sterile Neutrinos PPC07 6 May 07 3/5 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 Sterile Neutrinos PPC07 6 May 07 4/5 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

C. Giunti Sterile Neutrinos PPC07 6 May 07 5/5 MiniBooNE

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

5 C. Giunti Sterile Neutrinos PPC07 6 May 07 5/5 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 Sterile Neutrinos PPC07 6 May 07 6/5

7 Reactor Electron Antineutrino Anomaly C. Giunti Sterile Neutrinos PPC07 6 May 07 7/5 [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].8σ deficit Palo Verde RENO Rovno88 R = ± 0.04 Rovno9 SRP

8 5 MeV Bump ) ( C. Giunti Sterile Neutrinos PPC07 6 May 07 8/5 i Events / 0. MeV (Data - MC) / MC (a) Near Data MC Prompt Energy (MeV) Events / 0. MeV (Data - MC) / MC Entries / 50 kev Ratio to Prediction (Huber + Mueller) contribution χ 0 (b) Data Far Data MC Full uncertainty Reactor uncertainty ILL+Vogel Prompt Energy Prompt Energy (MeV) χ 4 0 Integrated Local p-value ( MeV windows) [RENO, arxiv: ] [Daya Bay, arxiv: ] It is correlated with the reactor activity. Cannot be explained by neutrino oscillations. Very likely due to theoretical miscalculation of the spectrum. 3% effect on total flux. It seems to be an excess!

9 Daya Bay Reactor Fuel Evolution Reactor ν e flux produced by the β decays of the fission products of 35 U, 38 U, 39 Pu, 4 Pu. σf [ 43 cm / fission] Best fit Average F Model (Rescaled) Daya Bay F 39 Linear fit: equal suppression (oscillations) disfavored at 3.σ. It is not clear which is the correspondence of the best linear fit with the suppression of the four fluxes. [Daya Bay, arxiv:704.08] σ39 [ 43 cm / fission] Daya Bay Huber model w/ 68% C.L. σ38 = (. ±. 0) 43 σ4 = (6. 04 ± 0. 60) 43 C.L 68% 95% 99.7% σ35 [ 43 cm / fission] 9 4 χ 4 9 Oscillations: χ /NDF = 7.9/ disfavored at.8σ. Uncertainty of theoretical fluxes in oscillation fit seems not to be taken in account because with different covariance matrices the models are not nested and one cannot apply the χ /NDF estimation. C. Giunti Sterile Neutrinos PPC07 6 May 07 9/5

10 C. Giunti Sterile Neutrinos PPC07 6 May 07 /5 Daya Bay χ min NDF GoF 35 U % OSC % All Reactors χ min NDF GoF 35 U % OSC % σ f / σ f th U OSC σ f / σ f th U OSC F i ILL Krasnoyarsk87 33 Krasnoyarsk87 9 Krasnoyarsk94 57 Krasnoyarsk99 34 SRP 8 SRP 4 Nucifer Daya Bay 0.5 Palo Verde Gosgen 38 Rovno88 S Daya Bay 0.74 Rovno88 I Rovno9 Rovno88 I Rovno88 S Daya Bay 0.87 Gosgen 46 Daya Bay 0.99 RENO Daya Bay 0.3 Rovno88 S Daya Bay 0.3 Bugey 4 Bugey 3 5 Bugey 3 40 Bugey 3 95 Gosgen 65 Daya Bay 0.33 F 35 F 38 F 39 F 4 Double Chooz Daya Bay Chooz L 3 Nucifer ILL Bugey 4 Bugey 3 5 Rovno9 Rovno88 I Rovno88 I Rovno88 S Rovno88 S SRP 8 SRP 4 Rovno88 S Krasnoyarsk87 33 Krasnoyarsk99 34 Gosgen 38 Bugey 3 40 Gosgen 46 Krasnoyarsk94 57 Gosgen 65 Krasnoyarsk87 9 Bugey 3 95 RENO Double Chooz Daya Bay Daya Bay 0.33 Daya Bay 0.3 Daya Bay 0.3 Daya Bay 0.99 Daya Bay 0.87 Daya Bay 0.74 Daya Bay 0.5 Palo Verde Chooz [CG, Laveder, Li, in preparation]

11 C. Giunti Sterile Neutrinos PPC07 6 May 07 /5 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

12 ε C. Giunti Sterile Neutrinos PPC07 6 May 07 /5 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.

13 C. Giunti Sterile Neutrinos PPC07 6 May 07 3/5 ] 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

14 C. Giunti Sterile Neutrinos PPC07 6 May 07 4/5 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]

15 C. Giunti Sterile Neutrinos PPC07 6 May 07 5/5 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 KARMEN+LSND 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 = anomaly Best Fit: m 4 =.7 ev sin ϑ ee = U e4 = 0.07 χ min /NDF = 63.0/74 GoF = 7% χ PG /NDF PG = 3.7/7 GoF PG = 6%

16 C. Giunti Sterile Neutrinos PPC07 6 May 07 6/5 Global ν e and ν e Disappearance + β Decay [Gariazzo, CG, Laveder, Li, arxiv: ] ν edis+β σ σ ν edis β Best Fit: m 4 =.7 ev sin ϑ ee = U e4 = 0.07 m 4 [ev ] + cm Losc 4 7 m at E [MeV] sin ϑ ee 0.3 at sin ϑ ee

17 The Race for ν e and ν e Disappearance C. Giunti Sterile Neutrinos PPC07 6 May 07 7/5 3 CeSOX shape (95% CL) CeSOX rate (95% CL) CeSOX rate+shape (95% CL) BEST (σ) IsoDAR@KamLAND (5yr, ) C ADS (5yr, ) KATRIN (90% CL) ν edis+β 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 edis+β 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] 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]

18 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 Sterile Neutrinos PPC07 6 May 07 8/5

19 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 CC+NC (06) IceCube: νµ + νµ (06) sin ϑ µµ C. Giunti Sterile Neutrinos PPC07 6 May 07 9/5

20 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 sin ϑ eµ C. Giunti Sterile Neutrinos PPC07 6 May 07 0/5 [Gariazzo, CG, Laveder, Li, arxiv: ] χ NO = σ anomaly Best Fit: m4 =.7 ev U e4 = 0.00 U µ4 = 0.05 χ min /NDF = 595./579 GoF = 3% χ PG /NDF PG = 7./ GoF PG =.7% Similar tension in 3+, 3+3,..., 3+N s [CG, Zavanin, MPLA 3 (05) ]

21 C. Giunti Sterile Neutrinos PPC07 6 May 07 /5 Effects of MINOS, IceCube and NEOS ( ) ν µ ( ) ν µ PrGlo6A PrGlo6A + MINOS PrGlo6A + IceCube PrGlo6A + MINOS + IceCube = PrGlo6B ( ) ν e ( ) ν e 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

22 C. Giunti Sterile Neutrinos PPC07 6 May 07 /5 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 rate+shape (95% CL) BEST (σ) IsoDAR@KamLAND (5yr, ) C ADS (5yr, ) KATRIN (90% CL) sin ϑ ee

23 C. Giunti Sterile Neutrinos PPC07 6 May 07 3/5 ( ) 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

C. Giunti Sterile Neutrinos PPC07 6 May 07 4/5 New Preliminary Bound from MINOS & MINOS+ Flanagan @

24 C. Giunti Sterile Neutrinos PPC07 6 May 07 4/5 New Preliminary Bound from MINOS & MINOS+ PPC07 PrGlo7 σ σ m 4 [ev ] MINOS 90% CL MINOS 99% CL MINOS 99.73% CL () MINOS & MINOS+ 90% CL sin ϑ µµ

25 C. Giunti Sterile Neutrinos PPC07 6 May 07 5/5 Conclusions Exciting indications of light sterile neutrinos at the ev scale: LSND ν µ ν e signal (caveat: single experimental signal). Gallium ν e disappearance (caveat: overestimated detector efficiency?). Reactor νe disappearance (caveat: Daya Bay reactor fuel evolution). 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).

Status of Light Sterile Neutrinos Carlo Giunti

Status of Light Sterile Neutrinos Carlo Giunti INFN, Torino, Italy EPS-HEP 07 07 European Physical Society Conference on High Energy Physics Venezia, Italy, 5- July 07 C. Giunti Status of Light Sterile