Neutrino Oscillations and Beyond Standard Model Physics University of Oslo Thomas Schwetz-Mangold Oslo, Norway, 29 April 2015 T. Schwetz 1
The Standard Model of particle physics T. Schwetz 2
Neutrinos are special ◮ very light (neutrino mass � 10 − 6 electron mass) ◮ the only (electrically) neutral fermions feel only the weak force and gravitation ◮ most abundant fermion in the Universe 336 cosmic neutrinos/cm 3 (comparable to 411 CMB photons/cm 3 ) ◮ every second 10 14 neutrinos from the Sun pass through your body ◮ neutrinos play a crucial role for ◮ energy production in the Sun ◮ nucleo sysnthesis: BBN, SN ◮ generating the baryon asymmetry of the Universe (maybe) T. Schwetz 3
◮ In the Standard Model neutrinos are massless. ◮ The observation of neutrino oscillations implies that neutrinos have non-zero mass. ⇒ Neutrino mass implies physics beyond the Standard Model. T. Schwetz 4
Outline Neutrino oscillations Absolute neutrino mass How to give mass to neutrinos Final remarks T. Schwetz 5
Neutrino oscillations Outline Neutrino oscillations Absolute neutrino mass How to give mass to neutrinos Final remarks T. Schwetz 6
Neutrino oscillations Flavour neutrinos neutrinos are “partners” of the charged leptons (doublet under the SU(2) gauge symmetry) ◮ A neutrino of flavour α is defined by the charged current interaction with the corresponding charged lepton, ex.: π + → µ + ν µ the muon neutrino ν µ comes together with the charged muon µ + T. Schwetz 7
Neutrino oscillations Lepton mixing ◮ Flavour neutrinos ν α are superpositions of massive neutrinos ν i : 3 � ν α = ( α = e , µ, τ ) U α i ν i i = 1 ◮ U α i : unitary lepton mixing matrix: Pontecorvo-Maki-Nakagawa-Sakata (PMNS) ◮ mismatch between mass and interaction basis ◮ in complete analogy to the CKM matrix in the quark sector T. Schwetz 8
Neutrino oscillations Neutrino oscillations detector neutrino source l α l β ν α ν β neutrino oscillations W W "long" distance e − i ( E i t − p i x ) | ν α � = U ∗ α i | ν i � | ν β � = U ∗ β i | ν i � � α i e − i ( E i t − p i x ) A ν α → ν β = � ν β | propagation | ν α � = U β i U ∗ i � 2 � � = � A ν α → ν β P ν α → ν β T. Schwetz 9
Neutrino oscillations Neutrino oscillations: 2-flavour limit � � P = sin 2 2 θ sin 2 ∆ m 2 L cos θ sin θ U = , − sin θ cos θ 4 E ν ∆ m 2 = m 2 2 − m 2 → oscillations are sensitive to mass differences 1 1 "short" "very long" "long" distance distance distance 0.8 2 4 π / ∆ m 0.6 P αβ ∆ m 2 L = 1 . 27 ∆ m 2 [ eV 2 ] L [ km ] 2 2 θ 0.4 sin 4 E ν E ν [ GeV ] 0.2 0 0.1 1 10 100 L / E ν (arb. units) T. Schwetz 10
Neutrino oscillations Neutrinos oscillate! ◮ atmospheric neutrinos Super-Kamiokande 1998: strong zenith angle dependence of the observed flux of ν µ consistent with ν µ → ν τ oscillations T. Schwetz 11
Neutrino oscillations Neutrinos oscillate! KamLAND reactor neutrino Data - BG - Geo ν CHOOZ data 1.4 e experiment ( ¯ ν e → ¯ ν e ) Expectation based on osci. parameters 1.2 determined by KamLAND Survival Probability 1 0.8 0.6 0.4 0.2 0 0 10 20 30 40 50 60 70 L /E (km/MeV) 0 ν e 2004: evidence for spectral distortion T. Schwetz 12
Neutrino oscillations Neutrinos oscillate! KamLAND reactor neutrino Data - BG - Geo ν CHOOZ data 1.4 e experiment ( ¯ ν e → ¯ ν e ) Expectation based on osci. parameters 1.2 determined by KamLAND Survival Probability 1 0.8 0.6 0.4 0.2 0 0 10 20 30 40 50 60 70 L /E (km/MeV) 0 ν e 2004: evidence for spectral distortion MINOS; T2K, 2015 ν µ → ν µ DayaBay, 2013 ¯ ν e → ¯ ν e T. Schwetz 12
Neutrino oscillations Global data on neutrino oscillations various neutrino sources, vastly different energy and distance scales: sun reactors atmosphere accelerators Homestake,SAGE,GALLEX KamLAND, D-CHOOZ SuperKamiokande K2K, MINOS, T2K SuperK, SNO, Borexino DayaBay, RENO OPERA ◮ global data fits nicely with the 3 neutrinos from the SM 3-neutrino osc. params.: θ 12 , θ 13 , θ 23 , δ, ∆ m 2 21 , ∆ m 2 31 ◮ a few “anomalies” at 2-3 σ : LSND, MiniBooNE, reactor anomaly, no LMA MSW up-turn of solar neutrino spectrum T. Schwetz 13
Neutrino oscillations 3-flavour global fit to oscillation data Global fit to 3-flavour oscillations with C. Gonzalez-Garcia, M. Maltoni, 1409.5439 2 x up − x low precision @ 3 σ : x up + x low Normal Ordering (∆ χ 2 = 0 . 97) Inverted Ordering (best fit) Any Ordering bfp ± 1 σ 3 σ range bfp ± 1 σ 3 σ range 3 σ range sin 2 θ 12 14% (4.6 o ) 0 . 304 +0 . 012 0 . 304 +0 . 012 0 . 270 → 0 . 344 0 . 270 → 0 . 344 0 . 270 → 0 . 344 − 0 . 012 − 0 . 012 33 . 48 +0 . 77 33 . 48 +0 . 77 θ 12 / ◦ 31 . 30 → 35 . 90 31 . 30 → 35 . 90 31 . 30 → 35 . 90 − 0 . 74 − 0 . 74 sin 2 θ 23 32% (15 o ) 0 . 451 +0 . 051 0 . 577 +0 . 027 0 . 382 → 0 . 643 0 . 389 → 0 . 644 0 . 385 → 0 . 644 − 0 . 026 − 0 . 035 42 . 2 +2 . 9 49 . 4 +1 . 6 θ 23 / ◦ 38 . 2 → 53 . 3 38 . 6 → 53 . 3 38 . 4 → 53 . 3 − 1 . 5 − 2 . 0 sin 2 θ 13 15% (1.2 o ) 0 . 0218 +0 . 0010 0 . 0219 +0 . 0010 0 . 0186 → 0 . 0250 0 . 0188 → 0 . 0251 0 . 0188 → 0 . 0251 − 0 . 0010 − 0 . 0011 8 . 50 +0 . 20 8 . 52 +0 . 20 θ 13 / ◦ 7 . 85 → 9 . 10 7 . 87 → 9 . 11 7 . 87 → 9 . 11 − 0 . 21 − 0 . 21 ∞ 305 +39 251 +66 δ CP / ◦ 0 → 360 0 → 360 0 → 360 − 51 − 59 14% ∆ m 2 21 7 . 50 +0 . 19 7 . 50 +0 . 19 7 . 03 → 8 . 09 7 . 03 → 8 . 09 7 . 03 → 8 . 09 10 − 5 eV 2 − 0 . 17 − 0 . 17 ∆ m 2 » – 11% +2 . 325 → +2 . 599 3 i +2 . 458 +0 . 046 − 2 . 448 +0 . 047 +2 . 317 → +2 . 607 − 2 . 590 → − 2 . 307 10 − 3 eV 2 − 0 . 047 − 0 . 047 − 2 . 590 → − 2 . 307 T. Schwetz 14
Neutrino oscillations Neutrino mass states and mixing NORMAL INVERTED ν e ν ν 2 3 ν 1 ν µ [mass] 2 ντ ν 2 ν 3 ν 1 T. Schwetz 15
Neutrino oscillations The SM flavour puzzle Lepton mixing: θ 12 ≈ 33 ◦ O ( 1 ) O ( 1 ) ǫ 1 U PMNS = √ O ( 1 ) O ( 1 ) O ( 1 ) θ 23 ≈ 45 ◦ 3 O ( 1 ) O ( 1 ) O ( 1 ) θ 13 ≈ 9 ◦ Quark mixing: θ 12 ≈ 13 ◦ 1 ǫ ǫ θ 23 ≈ 2 ◦ U CKM = ǫ 1 ǫ 1 θ 13 ≈ 0 . 2 ◦ ǫ ǫ T. Schwetz 16
Neutrino oscillations Neutrino masses NORMAL INVERTED ν e ν ν 2 3 ν 1 ν µ [mass] 2 ντ ν 2 ν 3 ν 1 ◮ at least two neutrinos are massive ◮ typical mass scales: � � ∆ m 2 ∆ m 2 21 ∼ 0 . 0086 eV , 31 ∼ 0 . 05 eV much smaller than other fermion masses ( m e ≈ 0 . 5 × 10 6 eV) ◮ 2 possibilities for the ordering of the mass states: normal vs inverted almost complete degeneracy in present data ( ∆ χ 2 ≈ 1) T. Schwetz 17
Neutrino oscillations Normal versus “abnormal” for inverted ordering leptons behave very different from quarks: ◮ the neutrino mass state mostly related to 12 10 t first generation would not be lightest charged fermions 10 b 10 c τ ◮ there is strong degeneracy between at least s 8 10 µ d two mass states: u 6 10 e ∆ m 2 m 2 − m 1 mass [eV] 21 4 ≡ = 2 deg 10 ¯ ( m 1 + m 2 ) 2 m 2 10 ∆ m 2 ∆ m 2 1 ≤ 1 21 21 ≈ 0 2 | ∆ m 2 31 | + m 2 2 | ∆ m 2 10 31 | QD 3 neutrinos -2 10 ν 1 ν 3 ν 2 IH NH � � m i -4 10 � − 2 1 . 3 × 10 − 3 ≤ deg ≤ 1 . 8 × 10 − 2 1 2 3 generation 0 . 5 eV T. Schwetz 18
Neutrino oscillations How to determine the mass ordering ◮ Find out whether the matter resonance in the 1-3 sector happens for neutrinos or antineutrinos ◮ long-baseline accelerator experiments: NOvA, LBNF ◮ atmospheric neutrino experiments: INO, PINGU, ORCA, HyperK ◮ Interference between oscillations with ∆ m 2 21 and ∆ m 2 31 ◮ reactor experiments at 50 km: JUNO, RENO-50 T. Schwetz 19
Neutrino oscillations Prospects for the mass ordering determination probability to exclude the wrong ordering at 3 σ Blennow, Coloma, Huber, TS, 2013 Blennow, TS, 2013, 2012 T. Schwetz 20
Neutrino oscillations CP violation Leptonic CP violation will manifest itself in a difference of the vacuum oscillation probabilities for neutrinos and anti-neutrinos Cabibbo, 1977; Bilenky, Hosek, Petcov, 1980, Barger, Whisnant, Phillips, 1980 Leptogenesis: ◮ provides mechanism to generate baryon asymmetry in the Universe ◮ requires CP violation at high temperatures (one of the Sacharov conditions) ◮ possible connection to CP violation in neutrino oscillations WARNING: model dependent! T. Schwetz 21
Neutrino oscillations The size of leptonic CP violation J = | Im ( U α 1 U ∗ α 2 U ∗ P ν α → ν β − P ¯ ν β ∝ J , β 1 U β 2 ) | ν α → ¯ J : leptonic analogue to Jarlskog-invariant Jarlskog, 1985 using the standard parameterization: 13 sin δ ≡ J max sin δ J = s 12 c 12 s 23 c 23 s 13 c 2 present data at 1 (3) σ NuFit 2.0 J max = 0 . 0329 ± 0 . 0009 ( ± 0 . 0027 ) compare with Jarlskog invariant in the quark sector: J CKM = ( 3 . 06 + 0 . 21 − 0 . 20 ) × 10 − 5 ◮ CPV for leptons might be a factor 1000 larger than for quarks ◮ OBS: for quarks we know J , for leptons only J max (do not know δ !) T. Schwetz 22
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