Neutrino Masses in Cosmology, Neutrinoless Double-Beta Decay and Direct Neutrino Masses Carlo Giunti

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1 Neutrino Masses in Cosmology, Neutrinoless Double-Beta Decay and Direct Neutrino Masses Carlo Giunti INFN, Sezione di Torino, and Dipartimento di Fisica Teorica, Università di Torino Neutrino Unbound: LIONeutrino01 Neutrinos at the forefront of elementary particle physics and astrophysics -4 October 01, Lyon, France C. Giunti Neutrino Masses LIONeutrino01 4 Oct 01 1/33

2 Three-Neutrino Mixing Paradigm m ν e ν µ ν τ m ν 3 ν m S ν 1 m A m A ν m S ν 1 Normal Spectrum ν 3 Inverted Spectrum m S ev m A ev C. Giunti Neutrino Masses LIONeutrino01 4 Oct 01 /33

3 Open Problems CP violation? Nova, LAGUNA, CERN-GS, HyperK,... Mass Hierarchy? Nova, Atmospheric Neutrinos, Day Bay II, Supernova Neutrinos,... Absolute Mass Scale? β Decay, Neutrinoless Double-β Decay, Cosmology,... Dirac or Majorana? Neutrinoless Double-β Decay,... Cosmology: see Verde and Saviano talks C. Giunti Neutrino Masses LIONeutrino01 4 Oct 01 3/33

4 1 Normal Spectrum 1σ σ 3σ Absolute Scale of Neutrino Masses Quasi Degenerate 1 Inverted Spectrum 1σ σ 3σ Quasi Degenerate m m 1, m, m 3 [ev] m 3 m m 1 Cosmological Limit m 3, m 1, m [ev] m 1 m 3 Cosmological Limit 10 4 Normal Hierarchy Lightest mass: m 1 [ev] 10 4 Inverted Hierarchy Lightest mass: m 3 [ev] m = m 1 + m 1 = m 1 + m S m 3 = m 1 + m 31 = m 1 + m A m 1 = m 3 m 31 = m 3 + m A m = m 1 + m 1 m 3 + m A Quasi-Degenerate for m 1 m m 3 m ν m A 5 10 ev C. Giunti Neutrino Masses LIONeutrino01 4 Oct 01 4/33

5 Tritium Beta-Decay 3 H 3 He+e dγ + ν e dt = (cosϑ CG F ) M F(E)pE (Q T) (Q T) m π 3 ν e Q = M3 H M3 He m e = 18.58keV Kurie plot [ ] 1/ dγ/dt K(T) = = (Q T) (Q T) m (cosϑ C G F ) νe M F(E)pE π 3 m νe <.ev (95% C.L.) K(T) T m νe = 0 m νe > 0 Q m νe Q Mainz & Troitsk [Weinheimer, hep-ex/010050] future: KATRIN [ start data taking in 015 sensitivity: m νe 0.eV C. Giunti Neutrino Masses LIONeutrino01 4 Oct 01 5/33

6 Neutrino Mixing = K(T) = [ (Q T) k U ek (Q T) m k ] 1/ K(T) Q m T Q m 1 Q analysis of data is different from the no-mixing case: N ( 1 parameters ) U ek = 1 k if experiment is not sensitive to masses (m k Q T) effective mass: m β = k U ek m k K = (Q T) [ U ek 1 mk (Q T) (Q T) U ek 1 1 ] mk (Q T) [ k ] k = (Q T) 1 1 mβ (Q T) (Q T) m (Q T) β C. Giunti Neutrino Masses LIONeutrino01 4 Oct 01 6/33

7 Predictions of 3ν-Mixing Paradigm m β = U e1 m 1 + U e m + U e3 m 3 m β [ev] Current Bound KATRIN Sensitivity IS NS m min Cosmological Limit [ev] 1σ σ 3σ Quasi-Degenerate: mβ m ν k U ek = mν Inverted Hierarchy: m β (1 s 13 ) m A m A Normal Hierarchy: m β s 1 c 13 m S +s 13 m A ev m β 4 10 ev Normal Spectrum C. Giunti Neutrino Masses LIONeutrino01 4 Oct 01 7/33

8 Neutrinoless Double-Beta Decay + β As 0 + β 76 3Ge β β 0 + Effective Majorana Neutrino Mass: m ββ = k 76 34Se U ek m k C. Giunti Neutrino Masses LIONeutrino01 4 Oct 01 8/33

9 Two-Neutrino Double-β Decay: L = 0 N(A,Z) N(A,Z +)+e +e + ν e + ν e (T ν 1/ ) 1 = G ν M ν Ï Ù second order weak interaction process in the Standard Model Ï Ù Neutrinoless Double-β Decay: L = N(A,Z) N(A,Z +)+e +e (T 0ν 1/ ) 1 = G 0ν M 0ν m ββ effective Majorana mass m ββ = Uek m k k Í Ñ Í Ï Ï Ù Ù C. Giunti Neutrino Masses LIONeutrino01 4 Oct 01 9/33

10 Effective Majorana Neutrino Mass m ββ = k U ek m k complex U ek possible cancellations m ββ = U e1 m 1 + U e e iα m + U e3 e iα 3 m 3 α = λ α 3 = (λ 3 δ 13 ) Im[m ββ ] Im[m ββ ] m ββ U e1 m 1 α U e3 e iα3 m 3 α 3 U e e iα m Re[m ββ ] m ββ U e3 e iα3 m 3 α α 3 U e e iα m U e1 m 1 Re[mββ ] C. Giunti Neutrino Masses LIONeutrino01 4 Oct 01 10/33

11 Experimental Bounds EXO ( 136 Xe) [PRL 109 (01) 03505] T 0ν 1/ > y (90% C.L.) = m ββ eV CUORICINO ( 130 Te) [AP 34 (011) 8] T 0ν 1/ > y (90% C.L.) = m ββ eV Heidelberg-Moscow ( 76 Ge) [EPJA 1 (001) 147] T 0ν 1/ > y (90% C.L.) = m ββ eV IGEX ( 76 Ge) [PRD 65 (00) 09007] T 0ν 1/ > y (90% C.L.) = m ββ eV NEMO 3 ( 100 Mo) [PRL 95 (005) 1830] T 0ν 1/ > y (90% C.L.) = m ββ 0.7.8eV C. Giunti Neutrino Masses LIONeutrino01 4 Oct 01 11/33

12 Experimental Positive Indication [Klapdor et al., MPLA 16 (001) 409] T 0ν 1/ = ( ) 105 y 6.5σevidence [MPLA 1 (006) 1547] Counts / kev SSE nb Rosen Primakov Approximation Q=039 kev Energy,keV [PLB 586 (004) 198] [MPLA 1 (006) 1547] m ββ = 0.3±0.03eV [MPLA 1 (006) 1547] very exciting: Majorana ν and large mass scale partially excluded by EXO and CUORICINO C. Giunti Neutrino Masses LIONeutrino01 4 Oct 01 1/33

13 Predictions of 3ν-Mixing Paradigm m ββ = U e1 m 1 + U e e iα m + U e3 e iα 3 m 3 Current Bound or Positive Indication Positive indication: tension with cosmology Quasi-Degenerate: m ββ [ev] IS NS m min [ev] Cosmological Limit 1σ σ 3σ m ββ m ν 1 s ϑ 1 s α Inverted Hierarchy: m ββ ma (1 s ϑ 1 sα ) Normal Hierarchy: m ββ 10 ev = Normal Spectrum m ββ s 1 m S +e iα s 13 m A.7+1.e iα 10 3 ev m ev cancellation? C. Giunti Neutrino Masses LIONeutrino01 4 Oct 01 13/33

14 ββ 0ν Decay Majorana Neutrino Mass m ββ can vanish because of unfortunate cancellations among m 1, m, m 3 contributions or because neutrinos are Dirac ββ 0ν decay can be generated by another mechanism beyond SM d d u e ββ 0ν = e u d d ββ 0ν u u e e W + W + ν e ν e (h = 1) ν e ν e (h = +1) [Schechter, Valle, PRD 5 (198) 951] [Takasugi, PLB 149 (1984) 37] Majorana Mass Term: L M el = 1 m ( ee ν c el ν el +ν el νel) c four-loop diagram calculation: m ee 10 4 ev [Duerr, Lindner, Merle, JHEP 06 (011) 091] C. Giunti Neutrino Masses LIONeutrino01 4 Oct 01 14/33

15 In any case finding ββ 0ν decay is important information to solve the Dirac-Majorana question in favor of Majorana On the other hand, it is not possible to prove experimentally that neutrinos are Dirac. A Dirac neutrino is equivalent to Majorana neutrinos with the same mass. Impossible to prove experimentally that mass splitting is exactly zero. C. Giunti Neutrino Masses LIONeutrino01 4 Oct 01 15/33

16 Beyond Three-Neutrino Mixing ν τ ν s1 ν µ ν e ν ν 3 ν 4 ν 5 ν 1 m 3 m 1 m m 4 m 5 logm ν s m SOL 3ν-mixing m ATM m SBL [see Schwetz and Cribier talks] C. Giunti Neutrino Masses LIONeutrino01 4 Oct 01 16/33

17 Sterile Neutrinos Sterile means no standard model interactions (e.g. ν c R = ν sl) Oscillation observables: Disappearance of active neutrinos (neutral current deficit) Indirect evidence through combined fit of data (current indication) Short-baseline anomalies + 3ν-mixing: m1 m 31 m ν 1 ν ν 3 ν 4... ν e ν µ ν τ ν s1... Neutrino number and mass observable: Number of thermalized relativistic particles in early Universe (BBN, CMB, BAO) m4 effects in cosmology (CMB, LLS), direct β-decay neutrino mass measurements and neutrinoless double-β decay (if Majorana) C. Giunti Neutrino Masses LIONeutrino01 4 Oct 01 17/33

18 Reactor Electron Antineutrino Anomaly [Mention et al, PRD 83 (011) ] [update in White Paper, arxiv: new reactor ν e fluxes [Mueller et al, PRC 83 (011) ] [Huber, PRC 84 (011) 04617].8σ anomaly R Reactor Rates Bugey3 15 Bugey3 40 Bugey3 95 Bugey4 ROVNO Gosgen 38 Gosgen 45 Gosgen 65 ILL Krasno 33 Krasno 9 Krasno 57 R = 0.93 ± 0.04 Average Rate L [m] C. Giunti Neutrino Masses LIONeutrino01 4 Oct 01 18/33

19 Gallium Anomaly Gallium Radioactive Source Experiments: GALLEX and SAGE Detection Process: ν e + 71 Ga 71 Ge+e ν e Sources: e + 51 Cr 51 V+ν e e + 37 Ar 37 Cl+ν e Anomaly supported by new 71 Ga( 3 He, 3 H) 71 Ge cross section measurement [Frekers et al., PLB 706 (011) 134] R GALLEX Cr1 SAGE Cr R = 0.84 ± 0.05 GALLEX Cr SAGE Ar E 0.7MeV L GALLEX = 1.9m L SAGE = 0.6m.9σ anomaly C. Giunti Neutrino Masses LIONeutrino01 4 Oct 01 19/33

20 3+1 SBL ν e and ν e Survival Probability P ( ) ν e ( ) ν e = 1 sin ϑ ee sin ( m ) 41 L 4E sin ϑ ee = 4 U e4 ( 1 U e4 ) standard parameterization U e1 = c 1 c 13 c 14 U e = s 1 c 13 c 14 U e3 = s 13 c 14 e iδ 13 U e4 = s 14 e iδ 14 sin ϑ ee = sin ϑ 14 C. Giunti Neutrino Masses LIONeutrino01 4 Oct 01 0/33

21 Global ν e and ν e Disappearance [Giunti, Laveder, Y.F. Li, Q.Y. Liu, H.W. Long, arxiv: ] [ev ] m [ev ] m % CL Gallium Reactors ν ec Sun Combined sin ϑ ee ν e + 1 C 1 N g.s. +e KARMEN + LSND [Conrad, Shaevitz, PRD 85 (01) ] [Giunti, Laveder, PLB 706 (011) 00] sin ϑ ee GAL+REA+ν ec+sun 68.7% CL (1σ) 90.00% CL 95.45% CL (σ) 99.00% CL 99.73% CL (3σ) solar ν e + KamLAND ν e + ϑ 13 [Giunti, Li, PRD 80 (009) ] [Palazzo, PRD 83 (011) ] [Palazzo, PRD 85 (01) ] C. Giunti Neutrino Masses LIONeutrino01 4 Oct 01 1/33

22 The existence of ν 4 with m 4 1eV can have dramatic effects not only on neutrino oscillations but also on all phenomena sensitive to the absolute value of neutrino masses: direct β-decay neutrino mass measurements neutrinoless double-β decay (if Majorana) cosmology Information on ν e and ν e disappearance is crucial for β decay and neutrinoless double-β decay ν e and ν e disappearance depends on sin ϑ ee = 4 U e4 (1 U e4 ) In β decay and neutrinoless double-β decay ν 4 contribution depends on U e4 C. Giunti Neutrino Masses LIONeutrino01 4 Oct 01 /33

23 Direct β-decay Neutrino Mass Measurements K(T)/(Q T) 10 3 [ev ] m T Q [ev] (sin ϑ ee, m 41 [ev ]) ( 0.1, 7.6 ) ( 0.1, ) ( 0.07, 0.9 ) ( 0.05, 0.46 ) GAL+REA+ν ec+sun sin ϑ ee GAL+REA+ν ec+sun 68.7% CL (1σ) 90.00% CL 95.45% CL (σ) 99.00% CL 99.73% CL (3σ) ( ) K(T) = 1 U e4 + U e4 m4 1 Q T (Q T) θ(q T m 4) C. Giunti Neutrino Masses LIONeutrino01 4 Oct 01 3/33

24 Mainz Neutrino Mass Experiment [Kraus, Singer, Valerius, Weinheimer, arxiv: ] C. Giunti Neutrino Masses LIONeutrino01 4 Oct 01 4/33

25 m 41 Upper Bound [ev ] m [ev ] m Osc. vs Mainz Osc. + Mainz % CL (1σ) 90.00% CL 95.45% CL (σ) 99.00% CL 99.73% CL (3σ) % CL (1σ) 90.00% CL 95.45% CL (σ) 99.00% CL 99.73% CL (3σ) sin ϑ ee sin ϑ ee C. Giunti Neutrino Masses LIONeutrino01 4 Oct 01 5/33

26 KATRIN Sensitivity 0 10 m41 ev m1 0, 90 C.L. m1 1 ev, 90 C.L. m1 ev, 90 C.L. global fit, 90 C.L. Bugey3, 99 C.L. Bugey4 Rovno, 99 C.L [Formaggio, Barrett, PLB 706 (011) 68] Sin Θs [Esmaili, Peres, PRD 85 (01) ] [see also Sejersen Riis, Hannestad, JCAP (011) 1475; Sejersen Riis, Hannestad, Weinheimer, PRC 84 (011) ] C. Giunti Neutrino Masses LIONeutrino01 4 Oct 01 6/33

27 Neutrinoless Double-β Decay χ GAL+REA+νeC+SUN EXO 90% CL 99.73% 95.45% 68.7% KK (4) m ββ [ev] 99% 90% m ββ = 4 k=1 U ek m k m (4) ββ = U e4 m 41 C. Giunti Neutrino Masses LIONeutrino01 4 Oct 01 7/33

28 Cancellation with m (light) ββ? [Barry, Rodejohann, Zhang, JHEP 07 (011) 091]; Li, Liu, PLB 706 (01) 406; Rodejohann, arxiv: ] m (light) 3 ββ = Uek m k k=1 m (4) ββ = U e4 m 41 m ββ = m (light) ββ +e iα 4 m (4) ββ m (4) ββ 10 ev Normal Hierarchy: m (light) ββ ev (95%CL) no cancellation is possible Inverted Hierarchy: m (light) ββ ev (95%CL) cancellation is possible Quasi-Degenerate: m (light) ββ ev cancellation is possible C. Giunti Neutrino Masses LIONeutrino01 4 Oct 01 8/33

29 10 1 EXO 90% CL 10 1 EXO 90% CL m ββ [ev] 10 m ββ [ev] Lightest mass: m 1 [ev] Normal Spectrum 1σ σ 3σ Lightest mass: m 3 [ev] Inverted Spectrum 1σ σ 3σ C. Giunti Neutrino Masses LIONeutrino01 4 Oct 01 9/33

30 Assumption: no cancellation 10 4 KK m ββ m (4) ββ = U e4 m EXO 90% CL m 41 = U e4 m(4) ββ [ev ] m ( mββ U e4 ) GAL+REA+νeC+SUN 68.7% CL (1σ) 90.00% CL 95.45% CL (σ) 99.00% CL 99.73% CL (3σ) sin ϑ ee C. Giunti Neutrino Masses LIONeutrino01 4 Oct 01 30/33

31 Cosmology N s = number of thermalized sterile neutrinos (not necessarily integer) [see Saviano talk] CMB and LSS in ΛCDM: N s = 1.3±0.9 m s < 0.66eV (95% C.L.) [Hamann, Hannestad, Raffelt, Tamborra, Wong, PRL 105 (010) ] N s = 1.61±0.9 m s < 0.70eV (95% C.L.) [Giusarma, Corsi, Archidiacono, de Putter, Melchiorri, Mena, Pandolfi, PRD 83 (011) 11503] { Ns 1 at 95% C.L. [Mangano, Serpico, PLB 701 (011) 96] BBN: N s = 0.0±0.5 [Pettini, Cooke, arxiv: ] CMB+LSS+BBN: N s = (95% C.L.) [Hamann, Hannestad, Raffelt, Wong, JCAP 1109 (011) 034] Standard ΛCDM: 3+1 allowed, 3+ disfavored C. Giunti Neutrino Masses LIONeutrino01 4 Oct 01 31/33

32 8 mν [ev] CMB WMAP +CMB SPT +H(z)+SNLS+BAO+WiggleZ CMB WMAP +H 0 CMB WMAP +H 0 +CMB SPT CMB WMAP +H 0 +H(z) CMB WMAP +BAO CMB WMAP +H 0 +WiggleZ N eff 68% and 95% CL [Riemer-Sørensen, Parkinson, Davis, Blake, arxiv: ] N eff Σ m ν CMB (blue), CMB+WL (red) CMB+BAO+OHD (magenta) CMB+BAO+SNIa (green) CMB+WL+BAO+OHD+SNIa (cyan) [Wang et al., arxiv: ] C. Giunti Neutrino Masses LIONeutrino01 4 Oct 01 3/33

33 Conclusions Cosmology Very powerful probe of neutrino number and masses Model dependent. Thermalization loophole Bright future (Plank,...) Direct β-decay Neutrino Mass Measurements Model independent and robust Sensitive to large neutrino masses beyond three-neutrino mixing KATRIN will start in 015 Unclear future (bolometers, project 8: radio-frequency) Neutrinoless Double-β Decay Crucial for Majorana discovery Sensitive to large neutrino masses beyond three-neutrino mixing Many running and future experiments C. Giunti Neutrino Masses LIONeutrino01 4 Oct 01 33/33