Oscillations Beyond Three-Neutrino Mixing Carlo Giunti INFN, - PowerPoint PPT Presentation

Oscillations Beyond Three-Neutrino Mixing Carlo Giunti INFN, Sezione di Torino giunti@to.infn.it Neutrino Unbound: http://www.nu.to.infn.it Neutrino 2016 XXVII International Conference on Neutrino Physics and Astrophysics 4-9 July 2016 – London, UK C. Giunti − Oscillations Beyond Three-Neutrino Mixing − Neutrino 2016 − 5 July 2016 − 1/37

Oscillations Beyond Three-Neutrino Mixing ◮ Light Sterile Neutrinos. ◮ Non-Unitarity of Mixing Matrix. ◮ Non-Standard Interactions. ◮ Magnetic Moments. C. Giunti − Oscillations Beyond Three-Neutrino Mixing − Neutrino 2016 − 5 July 2016 − 2/37

Indications of SBL Oscillations Beyond 3 ν C. Giunti − Oscillations Beyond Three-Neutrino Mixing − Neutrino 2016 − 5 July 2016 − 3/37

LSND [PRL 75 (1995) 2650; PRC 54 (1996) 2685; PRL 77 (1996) 3082; PRD 64 (2001) 112007] ν µ → ¯ ¯ ν e 20 MeV ≤ E ≤ 60 MeV ◮ Well-known source of ¯ ν µ µ + at rest → e + + ν e + ¯ ν µ L ≃ 30 m ν e + p → n + e + ¯ Well-known detection process of ¯ ν e ◮ But signal not seen by KARMEN at L ≃ 18 m with the same method [PRD 65 (2002) 112001] SBL � 0 . 2 eV 2 ≫ ∆ m 2 ∆ m 2 ATM ≫ ∆ m 2 ≈ 3 . 8 σ excess SOL C. Giunti − Oscillations Beyond Three-Neutrino Mixing − Neutrino 2016 − 5 July 2016 − 4/37

Gallium Anomaly Gallium Radioactive Source Experiments: GALLEX and SAGE e − + 51 Cr → 51 V + ν e e − + 37 Ar → 37 Cl + ν e ν e Sources: E ≃ 0 . 75 MeV E ≃ 0 . 81 MeV ν e + 71 Ga → 71 Ge + e − Test of Solar ν e Detection: � L � GALLEX = 1 . 9 m 1.1 GALLEX SAGE Cr1 Cr � L � SAGE = 0 . 6 m 1.0 R = N exp N cal GALLEX SAGE ≈ 2 . 9 σ deficit Cr2 Ar 0.9 SBL � 1 eV 2 ≫ ∆ m 2 ∆ m 2 ATM ≫ ∆ m 2 SOL 0.8 [SAGE, PRC 73 (2006) 045805; PRC 80 (2009) 015807] R = 0.84 ± 0.05 [Laveder et al, Nucl.Phys.Proc.Suppl. 168 (2007) 344; 0.7 MPLA 22 (2007) 2499; PRD 78 (2008) 073009; PRC 83 (2011) 065504] ◮ 3 He + 71 Ga → 71 Ge + 3 H cross section measurement [Frekers et al., PLB 706 (2011) 134] ◮ E th ( ν e + 71 Ga → 71 Ge + e − ) = 233 . 5 ± 1 . 2 keV [Frekers et al., PLB 722 (2013) 233] C. Giunti − Oscillations Beyond Three-Neutrino Mixing − Neutrino 2016 − 5 July 2016 − 5/37

Reactor Electron Antineutrino Anomaly [Mention et al, PRD 83 (2011) 073006; updated in White Paper, arXiv:1204.5379] New reactor ¯ ν e fluxes [Mueller et al, PRC 83 (2011) 054615; Huber, PRC 84 (2011) 024617] Bugey−3 Gosgen Rovno88 Palo Verde Nucifer 1.2 Bugey−4 ILL SRP Double Chooz Neutrino−4 Rovno91 Krasno Chooz Daya Bay 1.0 R = N exp N cal 0.8 R = 0.933 ± 0.021 0.6 10 2 10 3 10 L [m] SBL � 0 . 5 eV 2 ≫ ∆ m 2 ∆ m 2 ATM ≫ ∆ m 2 ≈ 3 . 2 σ deficit SOL C. Giunti − Oscillations Beyond Three-Neutrino Mixing − Neutrino 2016 − 5 July 2016 − 6/37

Beyond Three-Neutrino Mixing: Sterile Neutrinos m . . . . . . ν 5 ν s 2 ν 4 ν s 1 � 1 eV 2 ∆ m 2 SBL ν 3 ≃ 2.5 × 10 − 3 eV 2 ∆ m 2 ATM ν 2 ≃ 7.4 × 10 − 5 eV 2 ∆ m 2 SOL ν 1 ν e ν µ ν τ Terminology: a eV-scale sterile neutrino means: a eV-scale massive neutrino which is mainly sterile C. Giunti − Oscillations Beyond Three-Neutrino Mixing − Neutrino 2016 − 5 July 2016 − 7/37

Four-Neutrino Schemes: 2+2, 3+1 and 1+3 m m m m m m ν 4 ν 2 ν 2 ∆ m 2 ∆ m 2 ∆ m 2 ν 4 ν 4 ν 3 SOL SOL ATM ν 1 ν 1 ∆ m 2 ∆ m 2 ν 3 ATM ATM ν 2 ∆ m 2 SOL ν 1 ν 3 ∆ m 2 ∆ m 2 ∆ m 2 ∆ m 2 ∆ m 2 ∆ m 2 SBL SBL SBL SBL SBL SBL ν 3 ν 2 ∆ m 2 SOL ∆ m 2 ∆ m 2 ν 1 ν 4 ATM ATM ν 2 ν 2 ∆ m 2 ∆ m 2 ∆ m 2 ATM ν 4 ν 4 SOL SOL ν 3 ν 1 ν 1 ν 3 2+2 3+1 1+3 C. Giunti − Oscillations Beyond Three-Neutrino Mixing − Neutrino 2016 − 5 July 2016 − 8/37

2+2 Four-Neutrino Schemes m m ν 4 ν 2 ∆ m 2 ∆ m 2 SOL ATM ν 1 ν 3 ∆ m 2 ∆ m 2 SBL SBL ν 4 ν 2 ∆ m 2 ∆ m 2 ATM SOL ν 3 ν 1 ◮ After LSND (1995) 2+2 was preferred to 3+1, because of the 3+1 appearance-disappearance tension [Okada, Yasuda, IJMPA 12 (1997) 3669; Bilenky, CG, Grimus, EPJC 1 (1998) 247] ◮ This is not a perturbation of 3- ν Mixing = ⇒ Large active–sterile oscillations for solar or atmospheric neutrinos! C. Giunti − Oscillations Beyond Three-Neutrino Mixing − Neutrino 2016 − 5 July 2016 − 9/37

2+2 Schemes are Strongly Disfavored 50 solar + KamLAND r solar + KamLAND a 40 l o s ) t l a s 30 2 O global χ N PG 2 S ∆χ e r p ( 2 20 χ r a atm + K2K + SBL PC l o s 10 99% CL (1 dof) 0 0 0.2 0.4 0.6 0.8 1 0 0.2 0.4 0.6 0.8 1 0 η s η s Solar: Matter Effects + SNO NC Atmospheric: Matter Effects η s = | U s 1 | 2 + | U s 2 | 2 = 1 − | U s 3 | 2 + | U s 4 | 2 � η s < 0 . 25 (Solar + KamLAND) 99% CL: η s > 0 . 75 (Atmospheric + K2K) [Maltoni, Schwetz, Tortola, Valle, New J. Phys. 6 (2004) 122] C. Giunti − Oscillations Beyond Three-Neutrino Mixing − Neutrino 2016 − 5 July 2016 − 10/37

3+1 and 1+3 Four-Neutrino Schemes m m m m ν 2 ∆ m 2 ν 4 ν 4 ν 3 SOL ν 1 ∆ m 2 ∆ m 2 ATM ATM ν 2 ∆ m 2 SOL ν 1 ν 3 ∆ m 2 ∆ m 2 ∆ m 2 ∆ m 2 SBL SBL SBL SBL ν 3 ν 2 ∆ m 2 SOL ν 1 ∆ m 2 ∆ m 2 ATM ATM ν 2 ∆ m 2 ν 4 ν 4 SOL ν 1 ν 3 3+1 1+3 | U e 4 | 2 , | U µ 4 | 2 , | U τ 4 | 2 ≪ 1 | U s 4 | 2 ≃ 1 ◮ Perturbation of 3- ν Mixing: ◮ 1+3 schemes are disfavored by cosmology (ΛCDM): 3 � m k < 0 . 21 eV (95%, Planck TT + lowP + BAO) [arXiv:1502.01589] k =1 C. Giunti − Oscillations Beyond Three-Neutrino Mixing − Neutrino 2016 − 5 July 2016 − 11/37

Effective 3+1 SBL Oscillation Probabilities Appearance ( α � = β ) Disappearance � ∆ m 2 � � ∆ m 2 � 41 L 41 L ≃ sin 2 2 ϑ αβ sin 2 ≃ 1 − sin 2 2 ϑ αα sin 2 P SBL P SBL ( − ) ( − ) ( − ) ( − ) 4 E 4 E ν α → ν β ν α → ν α sin 2 2 ϑ αα = 4 | U α 4 | 2 � 1 − | U α 4 | 2 � sin 2 2 ϑ αβ = 4 | U α 4 | 2 | U β 4 | 2   U e 1 U e 2 U e 3 U e 4 ◮ CP violation is not observable in SBL   U µ 1 U µ 2 U µ 3 U µ 4   experiments! U =     U τ 1 U τ 2 U τ 3 U τ 4   ◮ Observable in LBL accelerator exp.   U s 1 U s 2 U s 3 U s 4 sensitive to ∆ m 2 [de Gouvea et al, PRD 91 (2015) ATM SBL 053005, PRD 92 (2015) 073012, arXiv:1605.09376; Palazzo et al, PRD ◮ 6 mixing angles 91 (2015) 073017, PLB 757 (2016) 142; Gandhi et al, JHEP 1511 (2015) 039] and solar exp. sensitive to ∆ m 2 ◮ 3 Dirac CP phases SOL ◮ 3 Majorana CP phases [Long, Li, CG, PRD 87, 113004 (2013) 113004] C. Giunti − Oscillations Beyond Three-Neutrino Mixing − Neutrino 2016 − 5 July 2016 − 12/37

3+1 Appearance-Disappearance Tension ν e DIS ν µ DIS sin 2 2 ϑ µµ ≃ 4 | U µ 4 | 2 sin 2 2 ϑ ee ≃ 4 | U e 4 | 2 ν µ → ν e APP sin 2 2 ϑ e µ = 4 | U e 4 | 2 | U µ 4 | 2 ≃ 1 4 sin 2 2 ϑ ee sin 2 2 ϑ µµ [Okada, Yasuda, IJMPA 12 (1997) 3669; Bilenky, CG, Grimus, EPJC 1 (1998) 247] 10 10 3 σ ν e DIS ◮ ν µ → ν e is quadratically suppressed! ν µ DIS DIS APP ◮ Similar constraint in + 2 [eV 2 ] 3+2, 3+3, . . . , 3+ N s 1 1 ∆ m 41 [CG, Zavanin, MPLA 31 (2015) 1650003] + 3+1 GLO Update of [Gariazzo, CG, Laveder, Li, Zavanin, JPG 43 (2016) 033001] 1 σ 2 σ with improved treatment of the MiniBooNE background disappearance 3 σ due to neutrino oscillations according to information from Bill Louis 10 − 1 10 − 1 (thanks!) 10 − 4 10 − 4 10 − 3 10 − 3 10 − 2 10 − 2 10 − 1 10 − 1 1 1 sin 2 2 ϑ e µ C. Giunti − Oscillations Beyond Three-Neutrino Mixing − Neutrino 2016 − 5 July 2016 − 13/37

Our Fit Collin, Arguelles, Conrad, Shaevitz Update of [Gariazzo, CG, Laveder, Li, Zavanin, [NPB 908 (2016) 354] JPG 43 (2016) 033001] 10 2 3+1 GLO 90% CL 99% CL 10 2 [eV 2 ] + 1 ∆ m 41 10 − 1 10 − 2 10 − 4 10 − 3 10 − 2 10 − 1 1 sin 2 2 ϑ e µ 41 = 1 . 75 eV 2 41 = 1 . 6 eV 2 ∆ m 2 ∆ m 2 Best Fit: Best Fit: | U e 4 | 2 = 0 . 027 | U µ 4 | 2 = 0 . 014 | U e 4 | 2 = 0 . 028 | U µ 4 | 2 = 0 . 014 GoF = 57% ( χ 2 GoF = 6% ( χ 2 min / NDF = 306 . 8 / 312) min / NDF = 304 . 0 / 268) GoF null = 4 . 4% ( χ 2 / NDF = 359 . 2 / 315) GoF null = 0 . 04% ( χ 2 / NDF = 355 . 2 / 271) ∆ χ 2 / NDF = 52 . 3 / 3 ( ≈ 6 . 7 σ ) ∆ χ 2 / NDF = 51 . 2 / 3 ( ≈ 6 . 6 σ ) C. Giunti − Oscillations Beyond Three-Neutrino Mixing − Neutrino 2016 − 5 July 2016 − 14/37

Our Fit Kopp, Machado, Maltoni, Schwetz Update of [Gariazzo, CG, Laveder, Li, Zavanin, [JHEP 1305 (2013) 050] JPG 43 (2016) 033001] 10 APP 90.00% CL APP 99.00% CL APP 99.73% CL DIS 90.00% CL DIS 99.00% CL DIS 99.73% CL 2 [eV 2 ] 1 ∆ m 41 10 − 1 10 − 4 10 − 3 10 − 2 10 − 1 sin 2 2 ϑ e µ ∆ m 2 41 = 0 . 93 eV 2 ∆ m 2 41 = 1 . 6 eV 2 Best Fit: Best Fit: | U e 4 | 2 = 0 . 023 | U µ 4 | 2 = 0 . 029 | U e 4 | 2 = 0 . 028 | U µ 4 | 2 = 0 . 014 GoF = 19% ( χ 2 GoF = 6% ( χ 2 min / NDF = 712 / 680) min / NDF = 304 . 0 / 268) GoF PG = 0 . 01% ( χ 2 GoF PG = 0 . 06% ( χ 2 / NDF = 15 . 0 / 2) PG / NDF = 18 . 0 / 2) C. Giunti − Oscillations Beyond Three-Neutrino Mixing − Neutrino 2016 − 5 July 2016 − 15/37