Carlo Giunti. CERN Particle and Astro-Particle Physics Seminar. work in collaboration with Mario Acero Marco Laveder Walter Winter

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1 Very-Short-BaseLine Electron Neutrino Disappearance Carlo Giunti INFN, Sezione di Torino, and Dipartimento di Fisica Teorica, Università di Torino Neutrino Unbound: 11 December 2009 CERN Particle and Astro-Particle Physics Seminar work in collaboration with Mario Acero Marco Laveder Walter Winter C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

2 Standard Model: Massless Neutrinos Standard Model: L c R =µ no Dirac mass term Ä D m D L R Majorana Neutrino: c = c R = R =µ Majorana mass term Ä M m M L c R Standard Model: Majorana mass term not allowed by SU(2) L U(1) Y (no Higgs triplet) C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

3 Neutrinos are special in the Standard Model: the only neutral fermions In extensions of the SM neutrinos can mix with non-sm fermions: L L = el I=12 e Y= 1 L Φ = + I=12 0 Y =+1 non-sm chiral fermion field f R = f C L Φ = i 2 Φ I=12 Y= 1 I=0 Y =0 Dirac mass term L L ΦfR + Majorana mass term f C R f R in some models f R is called right-handed neutrino: f R R If these non-sm fermions are light, they are called sterile neutrinos: sl C R Active neutrinos ( e ) can oscillate into sterile neutrinos ( s ) Extremely interesting window on physics beyond the SM Observable: disappearance of active neutrinos Many ( ) e and ( ) disappearance experiments We focus on e and e disappearance Gallium and MiniBooNE e anomalies and reactor e data C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

4 Experimental Evidences of Neutrino Oscillations ¼ ½ Homestake Kamiokande Solar GALLEX/GNO & SAGE e Super-Kamiokande m 2 SOL ³ (76 02) 10 5 ev 2 Reactor e disappearance Atmospheric Accelerator disappearance ¼ SNO BOREXino (KamLAND) Kamiokande IMB Super-Kamiokande MACRO Soudan-2 (K2K & MINOS) ½ tan 2 SOL ³ m 2 ATM ³ (24 01) 10 3 ev 2 sin 2 ATM ³ Two scales of m 2 : m 2 ATM ³ 30 m 2 SOL Large mixings: ATM ³ 45 Æ SOL ³ 34 Æ C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

5 Three-Neutrino Mixing «L = 3 k=1 U «k kl («= e ) three flavor fields: e,, three massive fields: 1, 2, 3 m m m 2 13 = m 2 2 m m 2 3 m m 2 1 m 2 3 = 0 m 2 SOL = m2 21 ³ (76 02) 10 5 ev 2 m 2 ATM ³ m2 31 ³ m2 32 ³ (24 01) 10 3 ev 2 C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

6 Allowed Three-Neutrino Schemes m 2 m 2 ν 3 ν 2 m 2 SOL ν 1 m 2 ATM m 2 ATM ν 2 m 2 SOL ν 1 ν 3 normal inverted different signs of m 2 31 ³ m2 32 absolute scale is not determined by neutrino oscillation data C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

7 Gallium Anomaly Gallium Radioactive Source Experiments Tests of the solar neutrino detectors GALLEX (Cr1, Cr2) and SAGE (Cr, Ar) Detection Process: e + 71 Ga 71 Ge + e e Sources: e + 51 Cr 51 V + e e + 37 Ar 37 Cl + e 51 Cr 37 Ar E [kev] B.R Ar (35.04 days) 37Cl (stable) 813 kev ν ( 9.8%) 811 kev ν (90.2%) [SAGE, PRC 73 (2006) , nucl-ex/ ] [SAGE, PRC 59 (1999) 2246, hep-ph/ ] C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

8 1.1 GALLEX Cr1 SAGE Cr p(measured)/p(predicted) GALLEX Cr2 SAGE Ar [SAGE, PRC 73 (2006) , nucl-ex/ ] R Ga = [SAGE, PRC 59 (1999) 2246, hep-ph/ ] C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

9 Deficit could be due to overestimate of ( e + 71 Ga 71 Ge + e ) Calculation: Bahcall, PRC 56 (1997) 3391, hep-ph/ / MeV 3/2 71 Ga 5/ MeV 1/2 71 Ge MeV G.S. related to measured (e + 71 Ge 71 Ga + e ): ( 51 Cr) = G.S. ( 51 Cr) G.S. ( 51 Cr) = cm 2 (1 0004) BGT 175keV BGT 500keV BGT G.S. BGT G.S. C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

10 Bahcall: [Bahcall, PRC 56 (1997) 3391, hep-ph/ ] from p + 71 Ga 71 Ge + n measurements [Krofcheck et al., PRL 55 (1985) 1051] BGT 175 kev BGT G.S µ BGT 175 kev BGT G.S. = BGT 500 kev BGT G.S. = lower limit: BGT 175 kev BGT G.S. = BGT 500 kev BGT G.S. = 0 3 upper limit: BGT 175 kev BGT G.S Haxton: BGT 500keV ( 51 Cr) = cm BGT G.S. = [Hata, Haxton, PLB 353 (1995) 422, nucl-th/ ; Haxton, PLB 431 (1998) 110, nucl-th/ ] a sophisticated shell model calculation is performed... for the transition to the first excited state in 71 Ge. The calculation predicts destructive interference between the (pn) spin and spin-tensor matrix elements. 1 ( 51 Cr) = cm 2 (1 0106) 1 C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

11 GALLEX SAGE Cr1 Cr2 Cr Ar R L 19m 06m R Ga = [SAGE, PRC 73 (2006) , nucl-ex/ ] m P ee(le) = 1 sin 2 2 sin 2 2 L 4E L osc 0.5 m =µ m 2 SBL 1eV2 =µ e s R = Ê dv L 2 È i (B.R.) i i P ee(le i ) Èi(B.R.) i i Ê dv L 2 C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

12 χ Ga 68.27% C.L. (1σ) 90.00% C.L % C.L. (2σ) 99.73% C.L. (3σ) m β < 2eV 2 min = 294 NdF = GoF = 23% [ev 2 ] 2 m SBL sin 2 2 = 022 m 2 = 198eV sin 2 SBL 2ϑ ee χ 2 [Acero, C.G, Laveder, PRD 78 (2008) , arxiv: ] C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

13 3+1 Four-Neutrino Mixing m 2 m 2 m 2 m 2 ν 2 ν 4 ν 4 ν 3 m 2 SOL m 2 ATM ν 2 m 2 ATM ν 1 m 2 SOL ν 1 ν 3 m 2 SBL m 2 SBL m 2 SBL m 2 SBL ν 3 ν 2 m 2 SOL m 2 ATM ν 2 m 2 ATM ν 1 m 2 SOL ν 4 ν 4 ν 1 ν 3 normal 3-inverted 4-inverted fully-inverted U e4 2 1 U U U s4 2 ³ 1 C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

14 m P SBL «= sin 2 2 SBL «sin 2 2 SBL L 4E («= ) sin 2 2 SBL «= 4U «4 2 U 4 2 P SBL ««= 1 sin 2 2 SBL ««sin2 m 2 SBL L 4E sin 2 2 SBL ««= 4U «4 2 1 U «4 2 U e1 U e2 U e3 U e4 U = U µ1 U τ1 U µ2 U τ2 U µ3 U τ3 U µ4 U τ4 sin 2 2 SBL ee sin 2 2 SBL ee ³ 022 µ U e4 2 ³ µ U e U s1 U s2 U s3 U s4 SBL C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

15 3 H 3 He + e + e K(T) = ÚÙ Ù Ø Tritium Beta-Decay Õ dγ dt = (coscgf)2 Å 2 F(E)pE (Q T) (Q T) 2 m e Q = M3 H M3 He 2 3 Kurie plot dγdt = (coscg F) 2 Å 2 F(E)pE m e = 1858keV (Q T) Õ 12 (Q T) 2 m 2 e 0.02 m e 22eV (95% C.L.) K(T) [kev] m νe = 0 m νe = 5 ev T [kev] Q m νe Q Mainz & Troitsk [Weinheimer, hep-ex/ ] future: KATRIN (start 2010) [hep-ex/ ] [hep-ex/ ] sensitivity: m e ³ 02eV C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

16 Neutrino Mixing: m e =µ m = k U ek 2 m 2 k 4-inverted and fully-inverted schemes U e1 2 + U e2 2 + U e3 2 ³ 1 Õ U e4 2 1 m ³ m 1 ³ m 2 ³ m 3 ³ msbl 2 m 2 SBL 5eV2 C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

17 Normal and 3-inverted schemes m 2eV =µ U e4 2 m 2 4 4eV 2 m 4 m 1 m 2 m 3 =µ m 2 4 ³ m 2 SBL m 2 SBL 4U e4 2 ev 2 sin 2 2 SBL ee = 4U e4 2 1 U e4 2 =µu e4 2 = 1 2 Õ U e =µ U e4 2 = Õ 1 1 sin 2 2 SBL ee 1 sin 2 2 SBL ee m 2 SBL 1 8 Õ ev 2 1 sin 2 2 SBL ee sin 2 2 SBL ee 002 µ msbl 2 800eV2 C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

18 LSND [PRL 75 (1995) 2650; PRC 54 (1996) 2685; PRL 77 (1996) 3082; PRD 64 (2001) ] e L ³ 30m 20MeV E 200MeV Beam Excess Beam Excess p(ν _ µ ν_ e,e+ )n p(ν _ e,e+ )n other L/E ν (meters/mev) m 2 (ev 2 /c 4 ) Karmen Bugey 90% (L max -L < 2.3) 99% (L max -L < 4.6) CCFR NOMAD sin 2 2θ m 2 LSND 02eV2 ( m 2 ATM m2 SOL ) C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

19 MiniBooNE [PRL 98 (2007) ] e L ³ 541m 475MeV E 3GeV Events / MeV Data ν e from µ + ν e from K 0 ν e from K π 0 misid Nγ dirt other Total Background QE E ν (GeV) Excess Events / MeV 0.8 data - expected background best-fit ν µ ν e sin 2θ=0.004, m =1.0eV sin 2θ=0.2, m =0.1eV QE E ν (GeV) [PRL 102 (2009) , arxiv: ] Low-Energy Anomaly! [arxiv: ] C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

20 MiniBooNE Low-Energy Anomaly Events / MeV Data ν e from µ + ν e from K 0 ν e from K π 0 misid Nγ dirt other Total Background [PRL 102 (2009) , arxiv: ] N the j = f P een cal e j + N cal j QE E ν (GeV) C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

21 Nj the = f P een cal e j + Ncal j Estimated 15% uncertainty of the calculated neutrino flux [MiniBooNE, PRD 79 (2009) , arxiv: ] is consistent with measured ratio of detected and predicted charged-current quasi-elastic events [MiniBooNE, PRL 100 (2008) , arxiv: ] We consider msbl 2 m2 VSBL 20eV2 Pee is practically constant in MiniBooNE L MB osc = 4E 400 m m2 LMB ³ 541 m Very-Short-BaseLine (VSBL) because oscillation length in Gallium Radioactive Source Experiments and Reactor Neutrino Experiments is extremely small: L osc (1 MeV) 10 cm C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

22 events / MeV E [MeV] MiniBooNE ν f bf bf ν P νe ν e cal cal N νe f bf ν N νµ f bf bf ν (P νe ν e N cal νe + N νµ cal ) [C.G, Laveder, PRD 80 (2009) , arxiv: ] No Osc. 2 min = 272 NdF = 10 GoF = 02% f = 115 Osc. 2 min = 177 NdF = 9 GoF = 38% f = 131 P ee = 072 C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

23 MiniBooNE- + Gallium + Reactors χ % 99% 95.45% 90% 68.27% MB ν MB ν + Ga Re MB ν + Ga + Re P νe ν e [C.G, Laveder, PRD 80 (2009) , arxiv: ] C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

24 MB- MB-+Ga Re MB-+Ga+Re 2 min No Osc. NDF GoF 0.2% 0.04% 89.8% 0.5% f bf min NDF Osc. GoF 3.8% 2.8% 82.7% 1.7% P bf ee f bf min PG NDF 1 2 GoF 12.4% 0.4% [C.G, Laveder, PRD 80 (2009) , arxiv: ] PG = Parameter Goodness-of-fit [Maltoni, Schwetz, PRD 68 (2003) , hep-ph/ ] C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

25 MiniBooNE Antineutrino Data [PRL 103 (2009) , arxiv: ] No Low-Energy Anomaly! C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

26 χ % 99% 95.45% 90% 68.27% MB ν MB MB + Ga + Re P νe ν e [C.G, Laveder, PRD 80 (2009) , arxiv: ] C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

27 MB- MB- +Re MB MB+Ga+Re 2 min No Osc. NDF GoF 7.6% 28.5% 0.2% 0.3% f bf min NDF Osc. GoF 5.0% 23.0% 0.9% 0.6% P bf ee f bf f bf min PG NDF GoF 100.0% 14.8% 4.1% N the j = f P een cal e j + Ncal j N the j = f P een cal e j + Ncal j [C.G, Laveder, PRD 80 (2009) , arxiv: ] C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

28 Tension between neutrino and antineutrino data could be due to: Statistical fluctuations. Underestimate of systematic uncertainties. Our hypothesis of VSBL e disappearance is excluded. Violation of CPT symmetry: P ee = P e e. «CP «T «CPT =µ P «= P ««= =µ P ««= P ««C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

29 CPT Violation? χ % 99% 95.45% 90% 68.27% CPT A ee A CPT ee P ee P e e 2 min = 399 NdF = 26 GoF = 40% A CPT ee = 017 [C.G, Laveder, PRD 80 (2009) , arxiv: ] C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

30 Future Tests of (V)SBL e and e Disappearance The hypothesis of VSBL e disappearance can be tested with high accuracy by future experiments with pure well-known electron neutrino beams: SAGE collaboration is planning a new source experiment ( e ) Beta-Beam experiments: N(AZ) N(AZ + 1) + e + e ( ) N(AZ) N(AZ 1) + e + + e ( + ) Neutrino Factory experiments: + + e + + e + e + e C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

31 Neutrino Factory Alternative Locations µ + Decay Straight ν µ + ν e Circumference: 1609 m µ ν µ + ν e Near Near Det. s=600 m d=2000 m d=50 m 755 m Far Near Det. To Far Det. [C.G, Laveder, Winter, PRD 80 (2009) , arxiv: ] Near Detectors: Systematic Uncertainties: Scintillator or Iron Calorimeter with perfect flavor identification Cross Section, Detector Normalization, Energy Resolution and Calibration, Backgrounds C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

32 d 50m200kgd 2km32t GLoBES 2009 m FDND FD only ND only FDND, no sys. Ref. beta beam Current limit sin 2 2Θ [C.G, Laveder, Winter, PRD 80 (2009) , arxiv: ] C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

33 CPT Violation? m P ee = 1 sin 2 2 sin 2 2 L 4E m P e e = 1 sin 2 2 sin 2 2 L 4E a CPT + m CPT m2 m 2 m 2 + m 2 C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

34 10 3 a CPT 10 3 m CPT True value ofm True value ofm True value of sin 2 2Θ True value of sin 2 2Θ [C.G, Laveder, Winter, PRD 80 (2009) , arxiv: ] ³ ³ ³ 0003 dashed lines: no averaging over decay straights C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

35 Conclusions The Gallium anomaly may be due to e s oscillations with sin and 1eV 2 m 2 800eV 2 These transitions may explain the MiniBooNE Low-Energy-Anomaly Tension between neutrino and antineutrino data could be an indication of CPT violation (P ee = P e e) (V)SBL e and e disappearance can be checked in future Beta-Beam experiments (pure e or e beam from nuclear decay) Neutrino Factory experiments (e and from + decay, or e and from decay), which can test also CPT violation. C. Giunti VSBL Electron Neutrino Disappearance 11 Dec

Sterile Neutrinos in July 2010

Sterile Neutrinos in July 2010 Sterile Neutrinos in July 0 Carlo Giunti INFN, Sezione di Torino Presidenza INFN, Roma, 19 July 0 Collaboration with Marco Laveder (Padova University) C. Giunti Sterile Neutrinos in July 0 Presidenza INFN,