Phenomenology of Sterile Neutrinos Carlo Giunti INFN, Sezione di Torino, and Dipartimento di Fisica Teorica, Università di Torino mailto://giunti@to.infn.it Neutrino Unbound: http://www.nu.to.infn.it Neutrini in Cosmologia Scuola di Formazione Professionale INFN 16-18 May 011, Padova C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 1/59
Three-Neutrino Mixing Paradigm ¼ ½ Homestake Kamiokande GALLEX/GNO & SAGE Super-Kamiokande Solar e Reactor e disappearance Atmospheric Accelerator disappearance ¼ SNO BOREXino (KamLAND) Kamiokande IMB Super-Kamiokande MACRO Soudan- (KK & MINOS) ½ m SOL ³ 76 10 5 ev sin SOL ³ 03 m ATM ³ 4 10 3 ev sin ATM ³ 050 Two scales of m µ Three-Neutrino Mixing m SOL = m 1 ³ 76 10 5 ev m ATM ³ m 31 ³ m 3 ³ 4 10 3 ev C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 /59
Three-Neutrino Mixing «L = 3 k=1 U «k kl («= e ) three flavor fields: e,, three massive fields: 1,, 3 m 1 + m 3 + m 13 = m m 1 +m 3 m +m 1 m 3 = 0 m SOL = m 1 ³ 76 10 5 ev m ATM ³ m 31 ³ m 3 ³ 4 10 3 ev C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 3/59
Allowed Three-Neutrino Schemes Ñ Ñ ¾ ËÍÆ Ñ ¾ ½ Ñ ¾ ÌÅ Ñ ¾ ÌÅ ¾ Ñ ¾ ËÍÆ ½ normal inverted different signs of m 31 ³ m 3 absolute scale is not determined by neutrino oscillation data C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 4/59
LSND [LSND, PRL 75 (1995) 650; PRC 54 (1996) 685; PRL 77 (1996) 308; PRD 64 (001) 11007] e L ³ 30m 0MeV E 00MeV Beam Excess 17.5 15 1.5 10 7.5 5.5 Beam Excess p(ν _ µ ν_ e,e+ )n p(ν _ e,e+ )n other 10 10 1 10-1 0 0.4 0.6 0.8 1 1. 1.4 10 - L/E ν (meters/mev) m (ev /c 4 ) Karmen Bugey 90% (L max -L <.3) 99% (L max -L < 4.6) CCFR NOMAD 10-3 10-10 -1 1 sin θ m LSND 0eV ( m ATM m SOL) C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 5/59
MiniBooNE Neutrinos [PRL 98 (007) 31801; PRL 10 (009) 10180] e L ³ 541m 475MeV E 3GeV Events / MeV 3.5 1.5 1 Data ν e from µ + ν e from K 0 ν e from K π 0 misid Nγ dirt other Total Background 0.5 0. 0.4 0.6 0.8 1 1. 1.4 1.5 1.6 3. QE E ν (GeV) Excess Events / MeV 0.8 data - expected background best-fit ν µ ν e 0.6 sin θ=0.004, m =1.0eV 0.4 sin θ=0., m =0.1eV 0. 0-0. 0. 0.4 0.6 0.8 1 1. 1.4 1.6 1.5 3. QE E ν (GeV) [MiniBooNE, PRL 10 (009) 10180, arxiv:081.43] Low-Energy Anomaly! [Djurcic, arxiv:0901.1648] C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 6/59
Events/MeV 0. MiniBooNE Antineutrinos [PRL 103 (009) 111801; PRL 105 (010) 181801] e L ³ 541m 475MeV E 3GeV 0.6 +/- ν e & ν e from µ Fit Region +/- ν e & ν e from K 0 ν e & ν e from K 0 π misid 0.4 Nγ dirt other Constr. Syst. Error Best Fit (E>475MeV) ) 4 10 10 68% CL 90% CL 99% CL KARMEN 90% CL BUGEY 90% CL /c Events/MeV 0.3 0. Data - expected background Best Fit sin θ=0.004, m =1.0eV (ev m 1 0.1 sin θ=0.03, m =0.3eV 0.0-1 10 LSND 90% CL -0.1 0. 0.4 0.6 0.8 1.0 1. 1.4 1.5 1.6 3.0 QE E ν (GeV) [MiniBooNE, PRL 105 (010) 181801, arxiv:1007.1150] - 10-3 10 LSND 99% CL Agreement with LSND e signal! - 10 sin (θ) Similar LE but different L and E =µ Oscillations! -1 10 1 C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 7/59
Beyond Three-Neutrino Mixing ν τ ν s1 ν µ ν e ν ν 3 ν 4 ν 5 ν 1 m 1 m m 3 ν s m 4 m 5 logm m SOL 3ν-mixing m ATM m SBL C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 8/59
Standard Model Neutrinos are the only massless fermions Neutrinos are the only fermions with only left-handed component L Extension of the SM: Massive Neutrinos Simplest extension: introduce right-handed component R Dirac mass m D R L + Majorana mass m M c R R el L L + er R R =µ 6 massive Majorana neutrinos C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 9/59
Sterile Neutrinos Light anti- R are called sterile neutrinos c R s (left-handed) Sterile means no standard model interactions Active neutrinos ( e ) can oscillate into sterile neutrinos ( s ) Observables: Disappearance of active neutrinos Indirect evidence through combined fit of data (current indication) Powerful window on new physics beyond the Standard Model C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 10/59
Cross-section (pb) 10 5 10 4 10 3 10 10 Number of Flavor and Massive Neutrinos? CESR DORIS PEP KEKB PEP-II PETRA TRISTAN 0 0 40 60 80 100 10 140 160 180 00 0 Γ Z = Z SLC LEP I e + e hadrons =eγ Z + q=t W + W - LEP II Centre-of-mass energy (GeV) σ had [nb] [LEP, Phys. Rept. 47 (006) 57, arxiv:hep-ex/0509008] Γ Zq q +Γ inv 30 0 10 N = 9840 0008 0 ALEPH DELPHI L3 OPAL average measurements, error bars increased by factor 10 ν 3ν 4ν 86 88 90 9 94 E cm [GeV] Γ inv = N Γ Z C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 11/59
e + e Z invisible a a =µ e a=active 3 light active flavor neutrinos mixing µ «L = N k=1 U «k kl «= e Mass Basis: 1 3 4 5 Flavor Basis: e s1 s ACTIVE STERILE N 3 no upper limit! C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 1/59
Cosmology N s = number of thermalized sterile neutrinos (not necessarily integer) CMB and LSS in ΛCDM: [Hamann, Hannestad, Raffelt, Tamborra, Wong, PRL 105 (010) 181301, arxiv:1006.576] N s = 161 09 m s 070eV (95% C.L.) [Giusarma, Corsi, Archidiacono, de Putter, Melchiorri, Mena, Pandolfi, arxiv:110.4774] BBN: N s = 0 059 [Cyburt, Fields, Olive, Skillman, AP 3 (005) 313, astro-ph/0408033] N s = 064 +040 035 [Izotov, Thuan, ApJL 710 (010) L67, arxiv:1001.4440] C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 13/59
Direct Searches of Active-Sterile Transitions C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 14/59
CCFR [PRD 59 (1999) 031101, arxiv:hep-ex/980903] NC interactions E 100GeV L ³ 14km C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 15/59
MINOS NC sample: 89% efficiency and 61% purity 97% of e -induced CC events misidentified as NC [arxiv:1104.39] Events/GeV 10 4 60 50 40 30 0 10 0 0 4 6 8 10 1 14 16 18 0 (GeV) E reco Near Detector Data Monte Carlo Prediction CC Background ν µ L ND = 104km Events/GeV 140 10 100 80 60 40 0 0 0 4 6 8 10 1 14 16 18 0 (GeV) E reco L FD = 735km Far Detector Data θ 13 = 0 θ = 11.5, δ = π, m3 >0 13 ν µ CC Background -3 m 3 =.3 10 ev sin θ 3 = 1 Model 13 /D.O.F. 3 4 34 f s m 4 = m 1 0 130.4/13 450 +7 7-00 +17 00 0. 115 18.5/13 456 +7 7-00 +5 00 0.40 m 4 m 3 0 130.4/1 450 +7 7 00 +5 00 00 +17 00 0. 115 18.5/1 456 +7 7 00 +5 00 00 +5 00 0.40 C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 16/59 90% C.L.
New Calculation of Reactor e Flux Th. A. Mueller, D. Lhuillier, M. Fallot, A. Letourneau, S. Cormon, M. Fechner, L. Giot, T. Lasserre, J. Martino, G. Mention, A. Porta, F. Yermia, Improved Predictions of Reactor Antineutrino Spectra, arxiv:1101.663 detected flux normalization is increased by about 3% Emitted spectrum Cross-section Detected spectrum Arbitrary Units 3 4 5 6 7 8 9 E ν (MeV) C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 17/59
G. Mention, M. Fechner, Th. Lasserre, Th. A. Mueller, D. Lhuillier, M. Cribier, A. Letourneau, The Reactor Antineutrino Anomaly, arxiv:1101.755 ratio of observed and predicted event rates: 0937 007 deviation from unity at 98.4% C.L.: reactor antineutrino anomaly 1.15 1.1 ILL Bugey 3/4 ROVNO Krasnoyarsk Goesgen Bugey3 Goesgen Krasnoyarsk 3 Goesgen Krasnoyarsk Bugey3 PaloVerde CHOOZ N OBS /(N EXP ) pred,new 1.05 1 0.95 0.9 0.85 0.8 0.75 0.7 10 1 10 10 3 Distance to Reactor (m) C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 18/59
New reactor neutrino flux has several implications: fit of solar and KamLAND data, determination of 13, short-baseline e disappearance,... Chooz limit on 13 Hint of 13 0 [Chooz, EPJC 7 (003) 331] [Fogli et al., PRL 101 (008) 141801] 10 0 8 6 4 dof χ contours CHOOZ simulation New spectra (σ f pred ) New spectra (σ f ano ) 0.16 0.14 dof χ contours Old spectra New spectra (σ f pred ) New spectra (σ f ano ) 10 1 8 6 CHOOZ (003) 0.1 0.1 KamLAND (010) Solar (ev ) m 31 4 10 8 sin θ 13 0.08 0.06 6 4 0.04 10 3 8 0.0 6 10 3 4 5 6 7 8 10 1 3 4 5 6 7 8 10 0 sin (θ 13 ) 0 0.1 0. 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 tan θ 1 [Mention et al., arxiv:1101.755] [Mention et al., arxiv:1101.755] C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 19/59
Four-Neutrino Schemes: + and 3+1 m ν 4 m ν 4 ν 3 m SBL m SBL ν 3 ν ν + ν 1 3+1 ν 1 C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 0/59
+ Four-Neutrino Schemes m m ν 4 ν m ATM ν 3 m SOL ν 1 m SBL m SBL ν m SOL ν 1 normal ν 4 m ATM ν 3 inverted C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 1/59
+ Schemes are strongly disfavored by solar and atmospheric data 50 χ 40 30 0 solar + KamLAND solar solar (pre SNO salt) global solar + KamLAND χ PG χ PC 10 99% CL (1 dof) atm + KK + SBL 0 0 0. 0.4 0.6 0.8 10 0. 0.4 0.6 0.8 1 η s η s matter effects + SNO NC 99% CL: s = U s1 + U s 1 s = U s3 + U s4 matter effects s 05 (solar + KamLAND) s 075 (atmospheric + KK) [Maltoni, Schwetz, Tortola, Valle, New J. Phys. 6 (004) 1, arxiv:hep-ph/040517] C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 /59
3+1 Four-Neutrino Schemes m m m m ν ν 4 ν 4 ν 3 m SOL m ATM ν m ATM ν 1 m SOL ν 1 ν 3 m SBL m SBL m SBL m SBL ν 3 ν m SOL m ATM ν m ATM ν 1 m SOL ν 4 ν 4 ν 1 ν 3 normal 3-inverted 4-inverted fully-inverted Perturbation of 3- Mixing U e4 1 U 4 1 U 4 1 U s4 ³ 1 C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 3/59
P «= = Effective SBL Oscillation Probabilities in 3+1 Schemes 4 k=1 4 k=1 U «ku ke ie kt U «ku ke i(e k E 1)t e ie 1t 4 k=1 U «ku k exp m k1 L E E k ³ p + m k m1 L m31 1 L p E E P «= U «1 U 1 +U «U +U «3 U 3 +U «4 m U L 4exp E 1 m 41 m U «1U 1 +U «U +U «3U 3 = Æ «U «4U 4 C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 4/59
P «= Æ «U «4 U 4 = Æ «+ U «4 U 4 Æ «U «4 m L 1 exp E cos m L E 1 cos m L E = Æ «U «4 Æ «U 4 1 cos m L E = Æ «4U «4 Æ «U 4 sin m L E «= =µ P «= 4U «4 U 4 sin m L 4E «= =µ P ««= 4U «4 1 U «4 sin m L 4E C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 5/59
m P «= sin «sin L 4E P ««m = 1 sin ««sin L 4E sin «= 4U «4 U 4 No CP Violation! sin ««= 4U «4 1 U «4 Perturbation of 3 Mixing U e4 1 U 4 1 U 4 1 U s4 ³ 1 U e1 U e U e3 U e4 sin ««1 U = U µ1 U τ1 U µ U τ U µ3 U τ3 U µ4 U τ4 U s1 U s U s3 U s4 SBL U «4 ³ sin ««4 C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 6/59
10 10 m [ev ] 1 3+1 Schemes GoF = 3% 10 1 PGoF = 089% 10 95.00% C.L. ν µ >ν e : LSND+KARMEN+MiniBooNE ν µ >ν e : MiniBooNE 10 4 10 3 10 10 1 1 sin ϑ eµ Tension between LSND + KARMEN + MiniBooNE e and MiniBooNE e =µ CP Violation? 3+ =µ CP Violation OK [Sorel, Conrad, Shaevitz, PRD 70 (004) 073004, hep-ph/030555; Maltoni, Schwetz, PRD 76, 093005 (007), arxiv:0705.0107; Karagiorgi et al, PRD 80 (009) 073001, arxiv:0906.1997] 3+1+NSI =µ CP Violation OK [Akhmedov, Schwetz, JHEP 10 (010) 115, arxiv:1007.4171] C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 7/59
e Disappearance and Disappearance 10 Reactor Rates 99.00% C.L. Bugey 3 (1995) Bugey 4 (1994) + Rovno (1991) Gosgen (1986) + ILL (1995) Krasnoyarsk (1994) 10 99.00% C.L. CDHSW (1984): ν µ ATM: ν µ + ν µ 10 10 m [ev ] 1 m [ev ] 1 10 1 10 1 10 10 10 1 1 sin ϑ ee New Reactor e Fluxes [Mueller et al., arxiv:1101.663] [Mention et al., arxiv:1101.755] 10 10 10 1 1 sin ϑ µµ ATM constraint on U 4 [Maltoni, Schwetz, PRD 76 (007) 093005, arxiv:0705.0107] C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 8/59
e disappearance experiments: sin ee = 4U e4 1 U e4 ³ 4U e4 disappearance experiments: sin = 4U 4 1 U 4 ³ 4U 4 e experiments: sin e = 4U e4 U 4 ³ 1 4 sin ee sin Upper bounds on sin ee and sin =µ strong limit on sin e [Okada, Yasuda, Int. J. Mod. Phys. A1 (1997) 3669-3694, arxiv:hep-ph/9606411] [Bilenky, Giunti, Grimus, Eur. Phys. J. C1 (1998) 47, arxiv:hep-ph/960737] C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 9/59
3+1 Schemes 10 99.00% C.L. Reactors CDHSW + Atm Disappearance LSND + MBν 10 m [ev ] 1 10 1 10 10 4 10 3 10 10 1 1 sin ϑ eµ C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 30/59
10 99.00% C.L. MBν + LSNDν Dis + KARMEN + MBν 10 m [ev ] 1 PGoF = 0006% 10 1 10 10 4 10 3 10 10 1 1 sin ϑ eµ Strong tension between e appearance and disappearance limits ( e e and mainly ) Tension reduced in 3+, 3+1+NSI CPT Violation? [Barger, Marfatia, Whisnant, PLB 576 (003) 303] [Giunti, Laveder, PRD 8 (010) 093016, PRD 83 (011) 053006] C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 31/59
Antineutrino Oscillations in 3+1 Schemes 10 10 m [ev ] 1 + m [ev ] 1 + 10 1 ν (3+1) 10 1 ν (3+1) 68.7% C.L. (1σ) 90.00% C.L. 95.45% C.L. (σ) 99.00% C.L. 99.73% C.L. (3σ) 68.7% C.L. (1σ) 90.00% C.L. 95.45% C.L. (σ) 99.00% C.L. 99.73% C.L. (3σ) 10 10 4 10 3 10 10 1 10 10 4 10 3 10 10 1 sin ϑ eµ sin ϑ µµ min = 870 NdF = 83 GoF = 36% m = 04eV sin e = 0016 sin ee = 000 sin = 065 Prediction: large SBL disappearance at m 01eV [Giunti, Laveder, PRD 83 (011) 053006, arxiv:101.067] C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 3/59
Gallium Anomaly Gallium Radioactive Source Experiments Tests of the solar neutrino detectors GALLEX (Cr1, Cr) 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] 747 75 47 43 811 813 B.R. 08163 00849 00895 00093 090 0098 37Ar (35.04 days) 37Cl (stable) 813 kev ν ( 9.8%) 811 kev ν (90.%) [SAGE, PRC 73 (006) 045805, nucl-ex/051041] [SAGE, PRC 59 (1999) 46, hep-ph/9803418] C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 33/59
1.1 GALLEX Cr1 SAGE Cr p(measured)/p(predicted) 1.0 0.9 0.8 0.7 GALLEX Cr SAGE Ar [SAGE, PRC 73 (006) 045805, nucl-ex/051041] R Gallex-Cr1 B = 0953 011 RB Gallex-Cr = 081 +010 011 RB SAGE-Cr = 095 01 RB SAGE-Ar = 0791 +0084 0078 [SAGE, PRC 59 (1999) 46, hep-ph/9803418] L GALLEX = 19m L SAGE = 06m R Ga B = 086 005 Bahcall cross section Only exp uncertainties! C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 34/59
Deficit could be due to overestimate of ( e + 71 Ga 71 Ge+e ) Calculation: Bahcall, PRC 56 (1997) 3391, hep-ph/9710491 3/ 0.500 MeV 3/ 71 Ga 5/ 0.175 MeV 1/ 71 Ge 0.33 MeV G.S. related to measured (e + 71 Ge 71 Ga+ e ): ( 51 Cr) = G.S. ( 51 Cr) G.S. ( 51 Cr) = 553 10 46 cm (1 0004) 3 Contribution of Excited States only 5%! 1+0669 BGT 175keV +00 BGT 500keV BGT G.S. BGT G.S. C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 35/59
Bahcall: [Bahcall, PRC 56 (1997) 3391, hep-ph/9710491] from p + 71 Ga 71 Ge+n measurements [Krofcheck et al., PRL 55 (1985) 1051] BGT 175keV 0056 µ BGT 175keV = 0056 BGT G.S. BGT G.S. 3 lower limit: BGT 175keV BGT G.S. = BGT 500keV BGT G.S. = 0 3 upper limit: BGT 175keV BGT G.S. 0056 ( 51 Cr) = 581 10 46 cm 1 +0036 008 Haxton: 1 BGT 500keV BGT G.S. = 0146 BGT 500keV BGT G.S. = 0146 =µ R Ga B = 086 006 [Hata, Haxton, PLB 353 (1995) 4, nucl-th/9503017; Haxton, PLB 431 (1998) 110, nucl-th/9804011] 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. ( 51 Cr) = 639 10 46 cm (1 0106) 1 =µ R Ga H = 078 013 C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 36/59
RH Ga = 078 013 R Ga = R Ga exp RGa the exp and the uncertainties added in quadrature probability distribution of ratio is not Gaussian p(r) 0 4 6 8 p R Ga Gallium B GALLEX Cr1 GALLEX Cr SAGE Cr SAGE Ar p R Ga 0.4 0.6 0.8 1.0 1. 1.4 p R Ga(r) = ½ p R Ga R Ga gs (rs)p exp R Ga (s)s ds R Ga = 076 +009 008 the R Gallex-Cr1 = 084 +013 01 R Gallex-Cr = 071 +01 011 R SAGE-Cr = 084 +014 013 R SAGE-Ar = 070 +010 009 [Giunti, Laveder, arxiv:1006.344] r C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 37/59
Gallium Radioactive Source Experiments are Short-BaseLine Neutrino Oscillation Experiments [Bahcall, Krastev, Lisi, PLB 348 (1995) 11] C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 38/59
m P SBL (LE) = 1 ee sin sin L 4E Êk È R k (sin m ) = dv L i bk i i k P SBL (LE ee i) Êk dv L È i bk i k i k = GALLEX-Cr1 GALLEX-Cr SAGE-Cr SAGE-Ar R k = R k exp Rk the p R (r) = ½ R k gs fully correlated theoretical uncertainty! k p R k exp (r k s) p R k the (s)s 4 ds Ä(sin m ) = p R ( R(sin m )) (sin m ) = ln Ä(sin m )+constant C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 39/59
χ 0 4 6 8 10 Gallium 68.7% C.L. (1σ) 90.00% C.L. 95.45% C.L. (σ) 99.00% C.L. 99.73% C.L. (3σ) No Osc. = 97 No Osc. disfavored at 99.3 % C.L (7) m [ev ] 1 + Osc. sin bf = 051 m bf = 4eV 10 1 10 10 1 sin ϑ 0 4 6 8 10 χ [Giunti, Laveder, arxiv:1006.344] C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 40/59
Reactor Antineutrino Anomaly R 0.7 0.8 0.9 1.0 1.1 1. Reactor Rates Bugey3 15 Bugey3 40 Bugey3 95 Bugey4 ROVNO Gosgen 38 Gosgen 45 Gosgen 65 ILL Krasno 33 Krasno 9 Krasno 57 0 0 40 60 80 100 L [m] Best Fits Reactor Rates Bugey 3 Spectra Combined R R R 0.80 0.90 1.00 0.75 0.85 0.95 1.05 0.0 0.5 1.0 1.5.0 New Reactor Neutrino Flux Bugey 3 Spectra L = 15 m 1 3 4 5 6 E e + [MeV] New Reactor Neutrino Flux Bugey 3 Spectra L = 40 m 1 3 4 5 6 E e + [MeV] New Reactor Neutrino Flux Bugey 3 Spectra L = 95 m 1 3 4 5 6 R rates = 0946 004 Improved hint of oscillations given by Bugey energy spectrum with old reactor fluxes sin bf = 0059 mbf = 189eV E e + [MeV] [Acero, Giunti, Laveder, PRD 78 (008) 073009, arxiv:0711.4] C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 41/59
Reactor Antineutrino Anomaly Gallium Neutrino Anomaly 10 10 + + m [ev ] 1 m [ev ] 1 Reactors Gallium 68.7% C.L. (1σ) 90.00% C.L. 95.45% C.L. (σ) 99.00% C.L. 99.73% C.L. (3σ) 68.7% C.L. (1σ) 90.00% C.L. 95.45% C.L. (σ) 99.00% C.L. 99.73% C.L. (3σ) 10 1 10 1 10 10 1 1 10 10 1 1 sin ϑ sin ϑ sin bf = 0059 sin bf = 051 m bf = 189eV m bf = 4eV C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 4/59
Gallium Anomaly + Reactor Anomaly 10 + + + min = 596 NdF = 71 m [ev ] 1 GoF = 83% sin = 011 m = 95eV 95.00% C.L. Gallium Reactors Combined PGoF = 46% 10 1 10 10 1 1 sin ϑ C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 43/59
Old Reactor e Fluxes New Reactor e Fluxes χ 0 4 6 8 10 99.73% 99% 95.45% 90% 68.7% Gallium Reactors Gallium + Reactors χ 0 4 6 8 10 99.73% 99% 95.45% 90% 68.7% Gallium Reactors Gallium + Reactors 10 3 10 10 1 1 sin ϑ PGoF = 3% 10 3 10 10 1 1 sin ϑ PGoF = 46% C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 44/59
3 H 3 He+e + e K(T) = ÚÙ Ù Ø Tritium Beta-Decay Õ dγ dt = (coscgf) Å F(E)pE (Q T) (Q T) m 3 e Q = M3 H M3 He m e = 1858keV 3 Kurie plot dγdt = (coscg F) Å F(E)pE (Q T) Õ 1 (Q T) m e K(T) 0.5 0.4 0.3 m νe = 0 0. 0.1 m νe = 100 ev 0 18.1 18. 18.3 18.4 18.5 18.6 T Q m νe Q m e ev (95% C.L.) Mainz & Troitsk [Weinheimer, hep-ex/010050] future: KATRIN (start 010) [hep-ex/0109033] [hep-ex/0309007] sensitivity: m e ³ 0eV C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 45/59
Neutrino Mixing =µ K(T) = (Q T) k U ek Õ(Q T) m k 1 Ã Ì µ ¼º¾ Í ¾ ½ ¼ ѽ ½¼ Î ¼º½ Í ¾ ¾ ¼ Ѿ ½¼¼ Î ¼º½ ¼º¼ ¼ ½º ½º ½º ½º ½º É Ñ ¾ Ì É Ñ ½ analysis of data is different from the no-mixing case: N 1 parameters k U ek = 1 if experiment is not sensitive to masses (m k Q T) effective mass: m = k U ek m k K = (Q T) U ek m 1 k ³ (Q T) (Q T) U ek 1 1 mk (Q T) k k Õ = (Q T) 1 1 m ³ (Q T) (Q T) m (Q T) C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 46/59
Neutrinoless Double-Beta Decay + β + 76 33As 0 + β 76 3Ge β β 0 + Effective Majorana Neutrino Mass: m = k 76 34Se U ek m k C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 47/59
Two-Neutrino Double- Decay: L = 0 Æ(AZ) Æ(AZ +)+e +e + e + e Ï Ù (T 1 ) 1 = G Å second order weak interaction process in the Standard Model Ï Ù Neutrinoless Double- Decay: L = Æ(AZ) Æ(AZ +)+e +e (T 0 1 ) 1 = G 0 Å 0 m Ï Í Ù effective Majorana mass m = k U ek m k Ñ Í Ï Ù C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 48/59
Implications of Gallium and Reactor Anomalies Decay ( ) 0 Decay χ 0 4 6 8 10 99.73% Gallium Reactors Tritium Combined 99% 95.45% 90% 68.7% 10 10 1 1 U e4 m [ev] χ 0 4 6 8 10 m = U ek mk m = k [Giunti, Laveder, In Preparation] 99.73% Gallium Reactors Tritium Combined 99% 95.45% 90% 68.7% 10 3 10 10 1 1 U e4 m [ev] U ek m k k C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 49/59
MiniBooNE Low-Energy Anomaly Events / MeV 3.5 1.5 1 Data ν e from µ + ν e from K 0 ν e from K π 0 misid Nγ dirt other Total Background 0.5 0. 0.4 0.6 0.8 1 1. 1.4 1.5 1.6 3. [PRL 10 (009) 10180, arxiv:081.43] Our Hypothesis: Nj the = f P een cal e j +N cal j QE E ν [Giunti, Laveder, PRD 77 (008) 09300, arxiv:0707.4593; PRD 80 (009) 013005, arxiv:090.199] C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 50/59 (GeV)
Nj the = f P een cal e j +N cal j Estimated 15% uncertainty of the calculated neutrino flux [MiniBooNE, PRD 79 (009) 0700, arxiv:0806.1449] is consistent with measured ratio 11 04 of detected and predicted charged-current quasi-elastic events [MiniBooNE, PRL 100 (008) 03301, arxiv:0706.096] We fit MiniBooNE e and data using the info at http://www-boone.fnal.gov/for_physicists/data_release/lowe/ C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 51/59
events / MeV 0.0 0.5 1.0 1.5.0.5 00 400 600 800 1000 100 1400 3000 E [MeV] MiniBooNE ν e N νe,the (j) νe,cal νe,j = f ν P νe νe N νe,j νµ,the νµ,cal N νe,j = f ν N νe,j N the νe,j = N νe,the νµ,the νe,j + N νe,j (b) [Giunti, Laveder, PRD 8 (010) 053005, arxiv:1005.4599] No Osc. & f = 1 min = 143+54 NdF = 3+16 GoF = 41% Our Hypothesis min = 0+76 NdF = 16 GoF = 89% f = 16 sin = 03 m = 184eV C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 5/59
MiniBooNE + Gallium m [ev ] χ 0 4 6 8 10 10 1 + MB + Ga 68.7% C.L. (1σ) 95.45% C.L. (σ) 99.73% C.L. (3σ) min = 3+9 NdF = 0 GoF = 93% sin = 07 m = 19eV PGoF = 93% 10 1 10 10 1 0 4 6 8 10 sin ϑ χ [Giunti, Laveder, PRD 8 (010) 053005, arxiv:1005.4599] C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 53/59
MiniBooNE + Gallium + Reactors χ 10 5 10 8 6 4 dof χ contours 1 dof χ profile 90.00 % 95.00 % 99.00 % (ev ) m new 10 1 10 0 8 6 4 8 6 4 10 1 8 6 4 1 dof χ profile 10 3 4 5 6 7 8 3 4 5 6 7 8 3 4 5 6 7 8 10 3 10 sin 10 1 10 0 (θ new ) 5 10 χ [Mention et al., arxiv:1101.755] C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 54/59
Future MiniBooNE is continuing to take antineutrino data. e + ICARUS@CERN-PS: L 1km E 1GeV [C. Rubbia et al, CERN-SPSC-011-01] ( ) ( ) e + ( ) ( ) + ( ) e ( ) e MicroBooNE will test the MiniBooNE low-energy anomaly by measuring 0 background. C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 55/59
e disappearance: new SAGE Gallium source experiments with spherical shells [Gavrin et al, arxiv:1006.103] CPT test: e and e disappearance Beta-Beam experiments: [Antusch, Fernandez-Martinez, PLB 665 (008) 190, arxiv:0804.80] N(AZ) N(AZ +1)+e + e ( ) N(AZ) N(AZ 1)+e + + e ( + ) Neutrino Factory experiments: [Giunti, Laveder, Winter, PRD 80 (009) 073005, arxiv:0907.5487] + +e + + e +e + e C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 56/59
New e and e radioactive source experiments with low-threshold neutrino elastic scattering detectors. Borexino: ( ) e +e ( ) e +e [Pallavicini, talk at BEYOND3NU] [Ianni, Montanino, Scioscia, EPJC 8 (1999) 609, arxiv:hep-ex/990101] LENS (Low Energy Neutrino Spectroscopy): e + 115 In 115 Sn+e + e +p n+e + [Agarwalla, Raghavan, arxiv:1011.4509] E th = 01MeV E th = 18MeV Spherical Gaseous TPC: [Vergados, Giomataris, Novikov, arxiv:1103.5307] Targets: 131 Xe, 40 Ar, 0 Ne, 4 He. Sources: 37 Ar, 51 Cr, 65 Zn, 3 P. C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 57/59
Conclusions 1 Suggestive LSND and MiniBooNE agreement on SBL e Hint in favor of sterile neutrinos is compatible with cosmological data, but mass is limited Two experimental tensions: LSND and MiniBooNE e vs MiniBooNE e (CP violation?) LSND and MiniBooNE e vs e and disappearance limits CPT-invariant 3+1 Four-Neutrino Mixing is strongly disfavored (no CP violation and tension between appearance and disappearance) 3+ can explain CP violation and reduce tension between appearance and disappearance with New Reactor e Fluxes 3+1+NSI has CP violation and reduced appearance-disappearance tension CPT-violating 3+1 Mixing =µ testable large SBL disappearance C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 58/59
Conclusions Interesting possible agreement of Gallium Anomaly (SBL e disappearance) Reactor Anomaly (SBL e disappearance) Testable Predictions: m 01 071eV () m 0011 015eV () Exciting experimental results in favor of sterile neutrinos. More work to do because interpretation is not clear: Explanation of all data needs at least two new physical effects. Without CPT violation tensions do not disappear completely. Possible that some experiments are giving misleading information. New short-baseline neutrino oscillation experiments are needed! C. Giunti Phenomenology of Sterile Neutrinos 16 May 011 59/59