Neutrino Mass: Overview of ββ 0ν, Cosmology and Direct Measurements Carlo Giunti

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1 Neutrino Mass: Overview of ββ 0ν, Cosmology and Direct Measurements Carlo Giunti INFN, Sezione di Torino, and Dipartimento di Fisica Teorica, Università di Torino Neutrino Unbound: Neutrino Town Meeting European Strategy for Neutrino Oscillation Physics - II May 2012, CERN C. Giunti Neutrino Mass: Overview of ββ 0ν, Cosmology and Direct Measurements 14 May /17

2 Three-Neutrino Mixing Paradigm ν e ν µ ν τ m 2 ν 3 m 2 ν 2 m 2 S ν 1 m 2 A m 2 A ν 2 m 2 S ν 1 ν 3 Normal Spectrum Inverted Spectrum absolute scale is not determined by neutrino oscillation data C. Giunti Neutrino Mass: Overview of ββ 0ν, Cosmology and Direct Measurements 14 May /17

3 Absolute Values of Neutrino Masses 1 Normal Spectrum 1σ 2σ 3σ Quasi Degenerate 1 Inverted Spectrum 1σ 2σ 3σ Quasi Degenerate m 2 m 1, m 2, m 3 [ev] m 3 m 2 m 1 Cosmological Limit m 3, m 1, m 2 [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 2 2 = m2 1 + m2 21 = m2 1 + m2 S m 2 3 = m2 1 + m2 31 = m2 1 + m2 A m 2 1 = m2 3 m2 31 = m2 3 + m2 A m 2 2 = m2 1 + m2 21 m2 3 + m2 A Quasi-Degenerate for m 1 m 2 m 3 m ν m 2 A ev C. Giunti Neutrino Mass: Overview of ββ 0ν, Cosmology and Direct Measurements 14 May /17

4 Tritium Beta-Decay 3 H 3 He+e dγ + ν e dt = (cosϑ CG F ) 2 M 2 F(E)pE (Q T) (Q T) 2 m 2π 2 3 ν e Q = M3 H M3 He m e = 18.58keV Kurie plot [ ] 1/2 dγ/dt K(T) = = (Q T) (Q T) 2 m (cosϑ C G F ) 2 2νe M 2 F(E)pE 2π 3 m νe < 2.2eV (95% C.L.) K(T) T m νe = 0 m νe > 0 Q m νe Q Mainz & Troitsk [Weinheimer, hep-ex/ ] future: KATRIN [ start data taking 2014 sensitivity: m νe 0.2eV C. Giunti Neutrino Mass: Overview of ββ 0ν, Cosmology and Direct Measurements 14 May /17

5 Neutrino Mixing = K(T) = [ (Q T) k U ek 2 (Q T) 2 m 2 k ] 1/2 K(T) Q m 2 T Q m 1 Q analysis of data is different from the no-mixing case: 2N ( 1 parameters ) U ek 2 = 1 k if experiment is not sensitive to masses (m k Q T) effective mass: m 2 β = k U ek 2 m 2 k K 2 = (Q T) 2 [ U ek 1 2 mk 2 (Q T) (Q T)2 U 2 ek ] mk 2 2 (Q T) [ 2 k ] k = (Q T) mβ 2 (Q T) (Q T) 2 m 2 2 (Q T) 2 β C. Giunti Neutrino Mass: Overview of ββ 0ν, Cosmology and Direct Measurements 14 May /17

6 Predictions of 3ν-Mixing Paradigm m 2 β = U e1 2 m U e2 2 m U e3 2 m 2 3 m β [ev] Current Bound KATRIN Sensitivity IS NS m min Cosmological Limit [ev] 1σ 2σ 3σ Quasi-Degenerate: mβ 2 m2 ν k U ek 2 = mν 2 Inverted Hierarchy: m 2 β (1 s2 13 ) m2 A m2 A Normal Hierarchy: m 2 β s2 12 c2 13 m2 S +s2 13 m2 A ev 2 If m β ev Normal Spectrum C. Giunti Neutrino Mass: Overview of ββ 0ν, Cosmology and Direct Measurements 14 May /17

7 Neutrinoless Double-Beta Decay 2 + β As 0 + β 76 32Ge β β 0 + Effective Majorana Neutrino Mass: m ββ = k 76 34Se U 2 ek m k C. Giunti Neutrino Mass: Overview of ββ 0ν, Cosmology and Direct Measurements 14 May /17

8 Two-Neutrino Double-β Decay: L = 0 N(A,Z) N(A,Z +2)+e +e + ν e + ν e (T 2ν 1/2 ) 1 = G 2ν M 2ν 2 Ï Ù second order weak interaction process in the Standard Model Ï Ù Neutrinoless Double-β Decay: L = 2 N(A,Z) N(A,Z +2)+e +e (T 0ν 1/2 ) 1 = G 0ν M 0ν 2 m ββ 2 effective Majorana mass m ββ = k U 2 ek m k Í Ñ Í Ï Ï Ù Ù C. Giunti Neutrino Mass: Overview of ββ 0ν, Cosmology and Direct Measurements 14 May /17

9 Effective Majorana Neutrino Mass m ββ = k U 2 ek m k complex U ek possible cancellations m ββ = U e1 2 m 1 + U e2 2 e iα 2 m 2 + U e3 2 e iα 3 m 3 α 2 = 2λ 2 α 3 = 2(λ 3 δ 13 ) Im[m ββ ] Im[m ββ ] m ββ U e1 2 m 1 α 2 U e3 2 e iα3 m 3 α 3 U e2 2 e iα2 m 2 Re[m ββ ] m ββ U e3 2 e iα3 m 3 α 2 α 3 U e2 2 e iα2 m 2 U e1 2 m 1 Re[mββ ] C. Giunti Neutrino Mass: Overview of ββ 0ν, Cosmology and Direct Measurements 14 May /17

10 Experimental Bounds CUORICINO ( 130 Te) [AP 34 (2011) 822] T 0ν 1/2 > y (90% C.L.) = m ββ eV Heidelberg-Moscow ( 76 Ge) [EPJA 12 (2001) 147] T 0ν 1/2 > y (90% C.L.) = m ββ eV IGEX ( 76 Ge) [PRD 65 (2002) ] T 0ν 1/2 > y (90% C.L.) = m ββ eV NEMO 3 ( 100 Mo) [PRL 95 (2005) ] T 0ν 1/2 > y (90% C.L.) = m ββ eV C. Giunti Neutrino Mass: Overview of ββ 0ν, Cosmology and Direct Measurements 14 May /17

11 Experimental Positive Indication [Klapdor et al., MPLA 16 (2001) 2409] T 0ν 1/2 = ( ) 1025 y 6.5σevidence [MPLA 21 (2006) 1547] Counts / kev SSE 2n2b Rosen Primakov Approximation Q=2039 kev Energy,keV [PLB 586 (2004) 198] [MPLA 21 (2006) 1547] the indication must be checked by other experiments m ββ = 0.32±0.03eV [MPLA 21 (2006) 1547] if confirmed, very exciting: Majorana ν and large mass scale C. Giunti Neutrino Mass: Overview of ββ 0ν, Cosmology and Direct Measurements 14 May /17

12 Predictions of 3ν-Mixing Paradigm m ββ = U e1 2 m 1 + U e2 2 e iα 2 m 2 + U e3 2 e iα 3 m 3 m ββ [ev] Current Bound or Positive Indication IS NS m min [ev] Cosmological Limit 1σ 2σ 3σ Positive indication: tension with cosmology Quasi-Degenerate: m ββ m ν 1 s 2 2ϑ 12 s 2 α 2 Inverted Hierarchy: m ββ ma 2(1 s2 2ϑ 12 sα 2 2 ) Normal Hierarchy: m ββ s 2 12 m 2 S +e iα s 2 13 m 2 A e iα 10 3 ev If m ββ 10 2 ev Normal Spectrum C. Giunti Neutrino Mass: Overview of ββ 0ν, Cosmology and Direct Measurements 14 May /17

13 New Experiments m ββ(mev) EXO200 GERDA1 CUORE 0 KamLAND Zen SNO GERDA2 CUORE NEXT SuperNemoD. MajoranaD. Experiments [Gomez-Cadenas, Martin-Albo, Mezzetto, Monrabal, Sorel, Riv. NC 35 (2012) 29] C. Giunti Neutrino Mass: Overview of ββ 0ν, Cosmology and Direct Measurements 14 May /17

14 Beyond Three-Neutrino Mixing ν τ ν s1 ν µ ν e ν 2 ν 3 ν 4 ν 5 ν 1 m 2 1 m 2 2 m 2 3 ν s2 m 2 4 m 2 5 logm 2 m 2 SOL 3ν-mixing m 2 ATM m 2 SBL C. Giunti Neutrino Mass: Overview of ββ 0ν, Cosmology and Direct Measurements 14 May /17

15 3+1 [ev 2 ] 2 m GLO+SUN 68.27% C.L. (1σ) 90.00% C.L % C.L. (2σ) 99.00% C.L % C.L. (3σ) + + DIS APP sin 2 2ϑ eµ DIS sin 2 2ϑ ee DIS sin 2 2ϑ µµ [Giunti, Laveder, Y.F. Li, in preparation] C. Giunti Neutrino Mass: Overview of ββ 0ν, Cosmology and Direct Measurements 14 May /17

16 β Decay 3+1 Predictions ββ 0ν Decay χ GLO 3+1 GLO+SUN 99.73% 99% 95.45% 90% 68.27% χ GLO 3+1 GLO+SUN 99.73% 99% 95.45% 90% 68.27% (4) m β [ev] m (4) β = U e4 m 2 41 m (4) β m (3ν) β (IH) (4) m ββ [ev] m (4) ββ = U e4 2 m 2 41 m (4) ββ m(3ν) ββ (IH) C. Giunti Neutrino Mass: Overview of ββ 0ν, Cosmology and Direct Measurements 14 May /17

17 Conclusions D.3 What is the likelihood of there being no interesting physics beyond measuring CP violation and mass hierarchy? Majorana Neutrinos: Very Likely ββ 0ν Decay; Majorana Phases; Lepton Number Violation; See-Saw Mechanism; Physics Beyond the Standard Model; Leptogenesis;... Sterile Neutrinos: Possible More Mixing Parameters: Masses, Mixing Angles, Phases; Rich Phenomenology at Easily Measurable ev Scale; Physics Beyond the Standard Model;......? C. Giunti Neutrino Mass: Overview of ββ 0ν, Cosmology and Direct Measurements 14 May /17