Invisible and Visible Neutrino Decay and Constraints on them from - PowerPoint PPT Presentation

Invisible and Visible Neutrino Decay and Constraints on them from Oscillation Experiments O. L. G. Peres 1 1 Instituto de Física Gleb Wataghin UNICAMP , Brazil NUFACT2017 25 October of 2017 unicampLogo 1 / 13

Neutrino Oscillations In the latest years there are stronger evidences for neutrino oscillation Daya Bay Experiment SNO experiment All evidences point to non-zero neutrino masses. unicampLogo 2 / 13

Why include neutrino decay in this picture? If the neutrino have mass then it can decay. Can we test the neutrino stability using present neutrino detectors? YES. The suppression factor of the decay is � L t � m � � φ decay − − τ LAB τ E ν = P decay = e = e φ Exclude PURE decay at 4 σ What happened when we have oscillation and decay AT same time? T.Kajita et al. , Nuclear Physics 908, 14 (2016) unicampLogo 3 / 13

Framework of Neutrino Decay We will assume that the Heavier neutrinos decay to lighter neutrinos (normal hierarchy) unicampLogo 4 / 13

Framework of Neutrino Decay Possible scenarios: Initial neutrino states final neutrino states − → � INVISIBLE final neutrino states VISIBLE  • Sterile states   INVISIBLE: • Below the threshold of experiment   • Depletion of event rates: even for NC rates � • Flavor states VISIBLE: • Increase/Depletion of event rates unicampLogo 4 / 13

Constrains on Invisible neutrino decay Invisible neutrino decay scenario for solar neutrinos: Berezhiani et al. 1992, Choubey it et al. 2000, Beacom/Bell 2002,Choubey/Goswami 2003 Berryman, Gouvea/Hernandez 2015, Picoreti et al. 2016 � L � � m 2 � � � P ( ν e → ν e ) = c 4 + s 4 P ⊙ e 1 P ⊕ 1 e + P ⊙ P ⊕ e 2 exp − 13 , 13 2 e τ 2 E ν • Picoreti et al. 2016 : energy distortion and seasonal dependence Analysis Neutrino Decay mode Limit τ 2 /m 2 > 7 . 2 × 10 − 4 s / eV Solar data Picoreti et al. ν 2 Invisible τ 2 /m 2 > 7 . 1 × 10 − 4 s / eV Solar data Berryman et al. ν 2 Invisible unicampLogo 5 / 13

Constrains on Invisible neutrino decay Invisible neutrino decay scenario for long-baseline experiments and atmospheric ν Barger et al. 1999, Fogli et al. 2004, Gonzalez-Garcia et al. 2008, Gomes et al. 2015, Choubey, Goswami and Pramani 2017 Analysis Neutrino Decay mode Limit Invisible τ 3 /m 3 > 2 . 9 × 10 − 10 s / eV Atmospheric and LBL data ν 3 Invisible τ 3 /m 3 > 2 . 8 × 10 − 12 s / eV MINOS and T2K data Gomes et al. ν 3 Invisible τ 3 /m 3 > 4 . 3 × 10 − 11 s / eV DUNE sensitivity (CHOUBEY et al. ) ν 3 and medium baseline reactor experiments Abrahão et al. 2015 Analysis Neutrino Decay mode Limit τ 3 /m 3 > 7 . 5 × 10 − 11 s / eV JUNO expected sensitivity ν 3 Invisible unicampLogo 5 / 13

Visible neutrino decay The visible neutrino scenario take into account the final states of neutrino decay: Lindner/Ohlsson/Winter 2001, Palomarez-Ruiz/ Pascoli/Schwetz 2005 Gago/Gomes 2 /Jones-Pérez/ Peres 2017, Coloma and Peres 2017 It is dependent of specific decay model of neutrino. We will assume a two-body neutrino decay ν ′ → ν + φ , φ is a scalar/pseudo-scalar. ν i ν 3 φ + g ′ g 3 i � 3 i L int = 2 ¯ 2 ¯ ν i iγ 5 ν 3 φ + h.c. , i =1 , 2 SCALAR PSEUDO-SCALAR unicampLogo 6 / 13

Visible neutrino decay • Helicity conserving decays : ν 3 → ν 1 + φ • Helicity non-conserving decays : ν 3 → ¯ ν 2 + φ Given a original ν µ flux, we have ( ν µ = U µ 1 ν 1 + U µ 2 ν 2 + U µ 3 ν 3 ). If ν 3 decay to ν 2 then the ν 2 mass eigenstate ( ν 2 = U ∗ e 2 ν e + U ∗ µ 2 ν µ + U ∗ τ 2 ν τ ) An original pure ν µ can from the chain above to have ν µ → ν e and also ν µ → ¯ ν e . : m heavy , m light and from �� × �� - � neutrino-scalar couplings. Γ ⨯ � � ( �� � ) �� × �� - � ++ Γ �� Coloma and Peres 2017 ++ Γ �� +- Γ �� �� × �� - � +- Γ �� �� × �� - � unicampLogo �� - � ����� ����� ����� � � ( �� ) 6 / 13

μ Analysis of Visible decay for MINOS and T2K Work in collaboration with Gago/Gomes 2 /Jones-Pérez/ Peres 2017, ν e : invisible decay black dashed , visible decay: solid black (both with δ CP = π/ 2 ) and standard oscillation is in δ CP = π/ 2( δ CP = − π/ 2 ) for red dotted( dashed) curve 6 5 4 ν 3 → ν 1 + φ /one non-zero coupling 3 2 1 0 0.0 0.2 0.4 0.6 0.8 1.0 1.2 E ν ( GeV ) unicampLogo 7 / 13

Analysis of Visible decay for MINOS and T2K ν µ neutrino events from MINOS Standard Oscillation 400 α Invisible Decay with 90% C.L. POT α Full Decay with 90% C.L. MINOS Data 20 300 10 × Events/GeV/10.71 ν Scalar µ 200 100 0 0 5 10 Energy (GeV) unicampLogo 7 / 13

Analysis of Visible decay for MINOS and T2K Allowed regions for MINOS and T2K: solid regions are standard oscillations and hollow regions are with decay 3 2 1 δ CP 0 - 1 + + x - 2 - 3 0.00 0.01 0.02 0.03 0.04 0.05 2 s 13 unicampLogo 7 / 13

Analysis of Visible decay for MINOS and T2K ∆ χ 2 for T2K and MINOS showing the constrains on the decay parameter: left : scalar, right :pseudo-scalar 6 6 T2K T2K 5 5 MINOS MINOS T2K + MINOS T2K + MINOS 4 4 Δχ 2 Δχ 2 3 3 2 2 1 1 0 0 10 - 5 10 - 4 10 - 5 10 - 4 α ( eV 2 ) α ( eV 2 ) unicampLogo 7 / 13

Visible neutrino decay for DUNE Made in collaboration with Pilar Coloma Assume ν 3 → ν 1 /ν 2 + φ with democratic couplings   0 0 0   1 0 0 ∆ m 2  U † + A 0 0  ,  21  H = U 0 0 0 2 E    − i Γ 3 ∆ m 2  0 0 0 0 0 31 2 E 2 Matter effects are important for DUNE � � m 2 1 + ∆ m 2 m 2 m 2 m 3 = 31 − → ˜ m 3 = 1 + ∆ ˜ 31 , → ˜ Affecting the total width as Γ 3 − Γ 3 ≡ ˜ m 3 / ( τ 3 E ) . unicampLogo 8 / 13

Visible neutrino decay for DUNE ��� �� ν � � � = � ν � � � = � ���� ��������� ��� �� ������ - ������ ���� ������ ���� �� �� ������ / ��� ������ / ��� �� ����� �� �� �� �� �� �� � � � � � � � � � � � � � � ν ( ��� ) � ν ( ��� ) ��� �� ν � � � = ��� �� ν � � � = ��� �� ���� ��������� ��� �� ������ - ������ ���� ������ ���� �� �� ������ / ��� ������ / ��� �� ����� �� �� �� �� �� �� � � � � � � � � � � � � � � ν ( ��� ) � ν ( ��� ) unicampLogo 8 / 13

Visible neutrino decay for DUNE Sensitivity for DUNE experiment � � �� - � ���� ( ��� ) ���� ( ��� ) ����� + ��� ( ��� ) ������� + ��� ( ��� ) �� - � �� - � �� - � � � ( �� ) unicampLogo 8 / 13

Conclusions • Neutrino decay can change the solar neutrino phenomenology? . • Solar ν data + KamLand/ Daya Bay: strongest bounds on ν 2 decay LBL experiments can give a bound on the ν 3 lifetime Invisible and visible ν decay have different behaviours: depletion and excess of events. T2K < 6 . 3 × 10 − 5 eV 2 , α ( p ) T2K < 5 . 6 × 10 − 5 eV 2 We got from T2K+MINOS present data α ( s ) TK2+MINOS < 7 . 8 × 10 − 5 eV 2 , TK2+MINOS < 6 . 9 × 10 − 5 eV 2 . α ( s ) α ( p ) unicampLogo 9 / 13

Conclusions Analysis Neutrino Decay mode Limit τ 2 /m 2 > 7 . 2 × 10 − 4 s / eV Solar data ν 2 Invisible τ 2 /m 2 > 7 . 1 × 10 − 4 s / eV Solar data ν 2 Invisible τ 3 /m 3 > 2 . 9 × 10 − 10 s / eV Atmospheric and LBL data ν 3 Invisible τ 3 /m 3 > 2 . 8 × 10 − 12 s / eV MINOS and T2K data ν 3 Invisible τ 3 /m 3 > 1 . 5 × 10 − 11 s / eV MINOS and T2K data ν 3 Visible τ 3 /m 3 > 7 . 5 × 10 − 11 s / eV JUNO expected sensitivity ν 3 Invisible τ 3 /m 3 > 1 . 95 − 2 . 6 × 10 − 10 s/eV DUNE expected sensitivity ν 3 Visible unicampLogo 9 / 13

Results for neutrino decay Stable neutrino � � ↑ � � Previous limit � Our limit: τ 2 m 2 > 7 . 7 × 10 − 4 s/eV 1 1 Similar bound from J.M.Berryman, A. Gouvea and D. Hernandez,Phys. unicampLogo Rev. D 92 , 073003 (2015) 10 / 13

Seasonal variation Solar neutrino fluxes have geometrical dependence on distance φ ⊙ φ ⊕ ν ν = 4 π ( L ( t )) 2 , φ ⊕ ν ( L max ) = (1 + ǫ 0 ) 2 ν ( L min ) (1 − ǫ 0 ) 2 → seasonal variation of solar neutrino flux φ ⊕ ǫ 0 is the Earth eccentricity With decay we have geometrial factor+decay factor � L � � m 2 � � � P ( ν e → ν e ) = c 4 + s 4 P ⊙ e 1 P ⊕ 1 e + P ⊙ P ⊕ e 2 exp 13 , − 13 2 e τ 2 E ν ( P ( ν e → ν e )) ( L min ) > ( P ( ν e → ν e )) ( L max ) � φ ⊕ � φ ⊕ � P ( ν e → ν e )( L min ) � φ ⊕ ν ( L min ) � ν ( L min ) � � ν ( L min ) � = > φ ⊕ φ ⊕ P ( ν e → ν e )( L max ) φ ⊕ ν ( L max ) ν ( L max ) ν ( L max ) decay no decay no decay Bigger seasonal effect with ν decay unicampLogo 11 / 13