Beyond Three-Neutrino Mixing Carlo Giunti

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1 Beyond Three-Neutrino Mixing Carlo Giunti INFN, Sezione di Torino, and Dipartimento di Fisica Teorica, Università di Torino Neutrino Unbound: νturn 0 Neutrino at the Turning Point 8- May 0, LNGS, Assergi, Italy C. Giunti Beyond Three-Neutrino Mixing 9 May 0 /4

2 Three-Neutrino Mixing Paradigm Solar ν e ν µ,ν τ Reactor ν e disappearance Atmospheric ν µ ν τ Accelerator ν µ disappearance Accelerator ν µ ν e Reactor ν e disappearance SNO, BOREXino Super-Kamiokande GALLEX/GNO, SAGE Homestake Kamiokande (KamLAND) Super-Kamiokande Kamiokande IMB, MACRO Soudan- (KK, MINOS, TK) ( m ev sin ϑ SOL 0.3 (TK, MINOS) Daya Bay, RENO Double Chooz m3.4 3 ev sin ϑ ) sin ϑ C. Giunti Beyond Three-Neutrino Mixing 9 May 0 /4

3 m (ev /c 4 ) LSND and MiniBooNE Antineutrinos [LSND, PRL 75 (995) 650; PRC 54 (996) 685; PRL 77 (996) 308; PRD 64 (00) 007] L 30m 0MeV E 00MeV Karmen Bugey [MiniBooNE, PRL 3 (009) 80; PRL 5 (0) 880] CCFR NOMAD L 54m 475MeV E 3GeV ) 4 /c (ev m 68% CL 90% CL 99% CL KARMEN 90% CL BUGEY 90% CL % (L max -L <.3) 99% (L max -L < 4.6) sin θ LSND 90% CL LSND 99% CL - sin (θ) Similar L/E but different L and E = Oscillations! - ν µ ν e m SBL 0.eV ( m ATM m SOL ) C. Giunti Beyond Three-Neutrino Mixing 9 May 0 3/4

4 R Reactor and Gallium Anomalies ν e Disappearance Reactor Rates Bugey3 5 Bugey3 40 Bugey3 95 Bugey4 ROVNO Gosgen 38 Gosgen 45 Gosgen 65 ILL Krasno 33 Krasno 9 Krasno L [m] R = 0.946±0.04 [Mention et al, PRD 83 (0) ] New Reactor ν e Fluxes [Mueller et al, PRC 83 (0) 05465] [Huber, PRC 84 (0) 0467] Average Rate p(measured)/p(predicted) ν e Disappearance GALLEX Cr SAGE Cr GALLEX Cr SAGE Ar [SAGE, PRC 73 (006) , nucl-ex/0504] L GALLEX =.9m L SAGE = 0.6m R = [Giunti, Laveder, PRC 83 (0) ] Haxton cross section with uncertainties [Haxton, PLB 43 (998) ] C. Giunti Beyond Three-Neutrino Mixing 9 May 0 4/4

5 Beyond Three-Neutrino Mixing ν τ ν s ν µ ν e ν ν 3 ν 4 ν 5 ν m m m 3 ν s m 4 m 5 logm m SOL 3ν-mixing m ATM m SBL C. Giunti Beyond Three-Neutrino Mixing 9 May 0 5/4

6 Standard Model Neutrinos are the only massless fermions Neutrinos are the only fermions with only left-handed component ν L Extension of the SM: Massive Neutrinos Simplest extension: introduce right-handed component ν R Dirac mass m D ν R ν L + Majorana mass m M ν c R ν R ν el, ν µl, ν τl + ν er, ν µr, ν τr = 6 massive Majorana neutrinos C. Giunti Beyond Three-Neutrino Mixing 9 May 0 6/4

7 Sterile Neutrinos Light anti-ν R are called sterile neutrinos ν c R ν sl (left-handed) Sterile means no standard model interactions Active neutrinos (ν e,ν µ,ν τ ) can oscillate into 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 Beyond Three-Neutrino Mixing 9 May 0 7/4

8 Effective SBL Oscillation Probabilities in 3+ Schemes ( ) m P να ν β = sin ϑ αβ sin 4 L 4E ( ) m P να ν α = sin ϑ αα sin 4 L 4E Perturbation of 3ν Mixing sin ϑ αβ = 4 U α4 U β4 No CP Violation! sin ϑ αα = 4 U α4 ( U α4 ) U e4, U µ4, U τ4, U s4 U e U e U e3 U e4 sin ϑ αα U = U µ U τ U µ U τ U µ3 U τ3 U µ4 U τ4 U s U s U s3 U s4 SBL U α4 sin ϑ αα 4 C. Giunti Beyond Three-Neutrino Mixing 9 May 0 8/4

9 CP Violation? m 4 [ev ] 3+ GoF = 36% 99% C.L. ν µ >ν e: LSND+KARMEN+MB0 ν µ >ν e: MiniBooNE 4 3 PGoF = 3.3% sin ϑ eµ 3+ = Tension between ν µ ν e and ν µ ν e data. 3+ = CP Violation [Sorel, Conrad, Shaevitz, PRD 70 (004) ], [Maltoni, Schwetz, PRD 76 (007) ], [Karagiorgi et al, PRD 80 (009) 07300], [Kopp, Maltoni, Schwetz, PRL 7 (0) 0980], [Giunti, Laveder, PRD 84 (0) ] 3++NSI = CP Violation [Akhmedov, Schwetz, JHEP (0) 5] C. Giunti Beyond Three-Neutrino Mixing 9 May 0 9/4

10 Effective SBL Oscillation Probabilities in 3+ Schemes φ kj = m kj L/4E η = arg[u e4 U µ4u e5 U µ5 ] P ( ) ν µ ( ) ν e = 4 U e4 U µ4 sin φ 4 +4 U e5 U µ5 sin φ 5 (+) +8 U µ4 U e4 U µ5 U e5 sinφ 4 sinφ 5 cos(φ 54 η) P ( ) ν α ( ) ν α = 4( U α4 U α5 )( U α4 sin φ 4 + U α5 sin φ 5 ) 4 U α4 U α5 sin φ 54 Good: CP violation can solve the ν µ ν e vs ν µ ν e tension. Bad: More parameters: 7 (vs 3 in 3+) sterile neutrinos are disfavored by BBN. A large sum of masses is disfavored by CMB+LSS. C. Giunti Beyond Three-Neutrino Mixing 9 May 0 /4

11 3+: MiniBooNE ν µ ν e and ν µ ν e P νµ νe MiniBooNE ν e exp P νµ νe <P > νµ νe E [MeV] P νµ νe MiniBooNE ν e exp P νµ νe <P > νµ νe E [MeV] P ( ) ν µ ( ) ν e = 4 U e4 U µ4 sin φ 4 +4 U e5 U µ5 sin φ 5 +4 U e4 U µ4 U e5 U µ5 cosη [ sin φ 4 +sin φ 5 sin φ 54 ] (+) U e4 U µ4 U e5 U µ5 sinη[sin(φ 4 ) sin(φ 5 )+sin(φ 54 )] C. Giunti Beyond Three-Neutrino Mixing 9 May 0 /4

12 Disappearance Constraints C. Giunti Beyond Three-Neutrino Mixing 9 May 0 /4

13 ν µ and ν µ Disappearance 99% C.L. CDHSW (984): ν µ ATM: ν µ + ν µ MINOS (0): ν µ [ev ] m 4 ATM constraint on U µ4 [Maltoni, Schwetz, PRD 76 (007) ] MINOS constraint on U µ4 [Giunti, Laveder, PRD 84 (0) ] sin ϑ µµ C. Giunti Beyond Three-Neutrino Mixing 9 May 0 3/4

14 ν e and ν e Disappearance 99% C.L. Bugey3 Bugey4+Rovno Gosgen+ILL Krasnoyarsk ν e C Gallium SUN New Reactor ν e Fluxes [Mueller et al., PRC 83 (0) 05465] [Mention et al., PRD 83 (0) ] [Huber, PRC 84 (0) 0467] [ev ] m 4 KARMEN + LSND ν e + C N g.s. +e [Conrad, Shaevitz, PRD 85 (0) 0307] [Giunti, Laveder, PLB 706 (0) 00] SUN&KamLAND + ϑ 3 [Giunti, Li, PRD 80 (009) 3007] [Palazzo, PRD 83 (0) 303] [Palazzo, PRD 85 (0) 07730] sin ϑ ee C. Giunti Beyond Three-Neutrino Mixing 9 May 0 4/4

15 SUN&KamLAND + ϑ 3 bound on U e4 [Giunti, Li, PRD 80 (009) 3007; Palazzo, PRD 83 (0) 303, PRD 85 (0) 07730] 3+ with simplifying assumptions: U µ4 = U τ4 = 0, no CP violation U e = c c 3 c 4 U e = s c 3 c 4 U e3 = s 3 c 4 U e4 = s 4 U s = c c 3 s 4 U s = s c 3 s 4 U s3 = s 3 s 4 U s4 = c 4 P νe ν e = c 4 3c 4 4P ν ν e ν e +s 4 3c 4 4 +s 4 4 P νe ν s = c4s 4 ( c 4 3 Pν ν e ν s +s3 4 + ) V = c 3 c 4 V CC c 3 s 4 V NC = ( U e + U e )V CC ( U s + U s )V NC C. Giunti Beyond Three-Neutrino Mixing 9 May 0 5/4

16 [Palazzo, PRD 83 (0) 303] sin ϑ 3 = 0.05±0.004 U e4 = sin ϑ 4 0.0(σ) [Palazzo, PRD 85 (0) 07730] C. Giunti Beyond Three-Neutrino Mixing 9 May 0 6/4

17 ν e disappearance experiments: 3+ sin ϑ ee = 4 U e4 ( U e4 ) 4 U e4 ν µ disappearance experiments: sin ϑ µµ = 4 U µ4 ( U µ4 ) 4 U µ4 ν µ ν e experiments: sin ϑ eµ = 4 U e4 U µ4 4 sin ϑ ee sin ϑ µµ Upper bounds on sin ϑ ee and sin ϑ µµ = strong limit on sin ϑ eµ [Okada, Yasuda, Int. J. Mod. Phys. A (997) ] [Bilenky, Giunti, Grimus, Eur. Phys. J. C (998) 47] C. Giunti Beyond Three-Neutrino Mixing 9 May 0 7/4

18 3+ without SUN&KL+ϑ σ 3+ with SUN&KL+ϑ σ νe Dis νµ Dis νe Dis νµ Dis Dis App Dis App [ev ] m 4 [ev ] m sin ϑ eµ GoF = 45% PGoF = 0.4% 3+ & 3+: Appearance-Disappearance tension sin ϑ eµ GoF = 38% PGoF = 0.3% Tension reduced in 3++NSI [Akhmedov, Schwetz, JHEP (0) 5] No tension in 3++CPTV [Barger, Marfatia, Whisnant, PLB 576 (003) 303] [Giunti, Laveder, PRD 8 (0) 09306, PRD 83 (0) ] C. Giunti Beyond Three-Neutrino Mixing 9 May 0 8/4

19 3+ with SUN&KamLAND+ϑ 3 χ [ev ] m % C.L. (σ) 90.00% C.L % C.L. (σ) 99.00% C.L % C.L. (3σ) 4 U e5 U µ σ App Dis + m 4 [ev ] χ U e4 U µ4 GoF = 46% PGoF = 0.9% 3+ is preferred to 3+ only for CP-violating MiniBooNE neutrino antineutrino difference C. Giunti Beyond Three-Neutrino Mixing 9 May 0 9/4

20 [ev ] m GLO 68.7% C.L. (σ) 90.00% C.L % C.L. (σ) 99.00% C.L % C.L. (3σ) DIS APP 4 3 DIS DIS [ev ] m 4 + sin ϑ eµ 3+ GLO+SUN 68.7% C.L. (σ) 90.00% C.L % C.L. (σ) 99.00% C.L % C.L. (3σ) sin ϑ ee + sin ϑ µµ + DIS APP 4 3 DIS DIS sin ϑ eµ sin ϑ ee sin ϑ µµ C. Giunti Beyond Three-Neutrino Mixing 9 May 0 0/4

21 Testable Implications χ GLO 3+ GLO+SUN β Decay (4) m β [ev] m β = k U ek mk m (4) β = U e4 m % 99% 95.45% 90% 68.7% χ (ββ) 0ν Decay 3+ GLO 3+ GLO+SUN 99.73% 95.45% 68.7% 3 (4) m ββ [ev] m ββ = k U ek m k m (4) ββ = U e4 m 4 99% 90% C. Giunti Beyond Three-Neutrino Mixing 9 May 0 /4

22 Cosmology N s = number of thermalized sterile neutrinos (not necessarily integer) CMB and LSS in ΛCDM: N s =.3±0.9 m s < 0.66eV (95% C.L.) [Hamann, Hannestad, Raffelt, Tamborra, Wong, PRL 5 (0) 830] N s =.6±0.9 m s < 0.70eV (95% C.L.) [Giusarma, Corsi, Archidiacono, de Putter, Melchiorri, Mena, Pandolfi, PRD 83 (0) 503] N s = (95% C.L.) [Archidiacono, Calabrese, Melchiorri, PRD 84 (0) 3008] N s = 0.±0.59 [Cyburt, Fields, Olive, Skillman, AP 3 (005) 33] BBN: N s = [Izotov, Thuan, ApJL 7 (0) L67] 0.35 N s at 95% C.L. [Mangano, Serpico, PLB 70 (0) 96] CMB+LSS+BBN: N s = (95% C.L.) [Hamann, Hannestad, Raffelt, Wong, JCAP 9 (0) 034] C. Giunti Beyond Three-Neutrino Mixing 9 May 0 /4

23 Thermalisation of Sterile Neutrinos [Hannestad, Tamborra, Tram, arxiv:04.586] 0.6 log ( δm s ) σ σ 3σ σ σ σ 3σ σ σ log ( δm s ) σ 3σ 3σ σ σ σ log (sin θ s ) log (sin θ s ) lepton asymmetry = 0 Color: thermalized iso-n s contours lepton asymmetry = Star: 3+ best fit [Giunti, Laveder, PLB 706 (0) 00] Dashed lines: CMB+LSS constraints [Hamann et al, PRL 5 (0) 830] C. Giunti Beyond Three-Neutrino Mixing 9 May 0 3/4

24 Conclusions Suggestive LSND, MiniBooNE, Reactor and Gallium indications in favor of short-baseline neutrino oscillations = sterile neutrinos Recent measurement of U e3 and SUN+KamLAND data restrict range of U e4 allowed by reactor short-baseline data for m SBL ev. 3+ Neutrino Mixing: No CP violation = Neutrinos vs Antineutrinos tension Appearance vs Disappearance tension Tension with standard cosmology (or large lepton asymmetry) 3+ Neutrino Mixing: CP violation = no Neutrinos vs Antineutrinos tension Appearance vs Disappearance tension More tension with standard cosmology (or large lepton asymmetry) Simpler 3+ Neutrino Mixing may be enough (Occam s Razor). New short-baseline neutrino oscillation experiments are needed! C. Giunti Beyond Three-Neutrino Mixing 9 May 0 4/4