Neutrino properties: nature, mass & CP violation I. Schienbein LPSC prepared together with P. Serpico (LAPTH) and A. Wingerter (LPSC) Kick-off meeting, 12/10/2012, Annecy Friday, October 12, 12 Facts of life with neutrinos Friday, October 12, 12 Citation: J. Beringer et al. (Particle Data Group), PR D86, 010001 (2012) (URL: http://pdg.lbl.gov) − p η L,B < 8.9 × 10 6 CL=90% 475 D86 − p π0 ηCitation: J. Beringer et al. (ParticleL Data,B Group),< PR 2.7 , 010001 (2012)× (URL:10 5 http://pdg.lbl.gov)CL=90% 360 − − Λπ L,B < 7.2 × 10 8 CL=90% 525 −Citation: J. Beringer et al. (Particle Data Group), PR D86, 010001 (2012)× (URL:−−6 http://pdg.lbl.gov) Λpπη L,B << 81..94 ×1010 7 CL=90%CL=90% 475 525 − − 0 L B < . × −5 ep πlightη boson LF, < 22.77 ×1010− 3 CL=90%CL=95% 360– p η − L,B < 8.9 × 10 −6 CL=90% 475 Λ−π L,B < 7.2 ××10 −83 CL=90% 525 µ light0 boson LF < 5 10−5 CL=95% – p π −η L,B < 2.7 ××10 −7 CL=90% 360 Λπ− L,B < 1.4 10− CL=90% 525 Λ− L,B < 7.2 × 10 −8 CL=90% 525 e π light boson LF < 2.7 × 10 3 CL=95% – − −7 Λ−π L,B < 1.4 ××10 −3 CL=90% 525 µHeavy− light boson Charged LeptonLF Searches< 5 10− CL=95% – e light boson LF < 2.7 × 10 3 CL=95% – Neutrino properties:− × −3 LF µ light boson± < 5 10 CL=95% – HeavyL Charged–chargedlepton Lepton Searches Mass m > 100.8GeV,CL=95%[h] Decay to ν W . What we knowHeavy± Charged in 2012 Lepton Searches ±± LL± –stablechargedheavylepton–chargedlepton ± [h] L± Mass–chargedleptonMass mm >> 102100.6GeV,CL=95%8GeV,CL=95% Decay to ν W . ± L Mass–stablechargedheavyleptonm > 100.8GeV,CL=95%[h] Decay to ν W . ± • very weakly interacting, NeutrinoL± –stablechargedheavyleptonMass Propertiesm > 102.6GeV,CL=95% Mass m > 102.6GeV,CL=95% electrically neutral, spin 1/2, SeeNeutrino the note Properties on “Neutrino properties listings” in the Particle Listings. Mass m < 2eV (tritiumdecay) tiny mass Neutrino Properties See the noteMean on “Neutrino life/mass, propertiesτ/m > 300 listings” s/eV, in CL the = Partic 90%le Listings. (reactor) Mean life/mass, τ/m > 7 × 109 s/eV (solar) See the noteMass on “Neutrinom < 2eV properties (tritiumdecay) listings” in the Particle Listings. MeanMean life/mass, life/mass, τ/m > 30015.4s/eV,CL=90% s/eV, CL = 90% (reactor) (accelerator) long lived (or stable), Mass m < 2eV (tritiumdecay)− • Magnetic moment µ<m 0.×32 ×910 10 µ ,CL=90% (solar) MeanMean life/mass, life/mass, ττ//m >> 3007 s/eV,10 s/eV CL =B 90%(solar) (reactor) tiny or vanishing magnetic MeanMean life/mass, life/mass, ττ//mm >> 715×.4s/eV,CL=90%109 s/eV (solar) (accelerator) µ< . × −10 µ Number ofMeanMagnetic Neutrino life/mass, moment Typesτ/m > 150 32.4s/eV,CL=90%10 B ,CL=90% (accelerator) (solar) moment −10 Magnetic moment µ<0.32 × 10 µB ,CL=90% (solar) NumberNumber of NeutrinoN =2 Types.984 ± 0.008 (Standard Model fits to LEP data) NumberNumber of NeutrinoN =2 Types.92 ± 0.05 (S = 1.2) (Direct measurement of NumberinvisibleN =2Z width).984 ± 0.008 (Standard Model fits to LEP data) • 3 light ‘SM families’ (νe ,νμ , ντ) NumberNumber NN =2=2..98492 ±±00..05008 (S (Standard = 1.2) (DirectModel fits measurement to LEP data) of invisibleN Z .width)± . NeutrinoNumber Mixing =292 0 05 (S = 1.2) (Direct measurement of invisible Z width) TheNeutrino following Mixing values are obtained through data analyses based on theNeutrinoCitation: 3-neutrino J. Beringer Mixing mixinget al. (Particle scheme Data described Group), PR D86 in, the 010001 review (2012) (URL: “Neutr http://pdg.lbl.gov)ino Mass,The following Mixing, andvalues Oscillations” are obtained by through K. Nakamura data analyses and S.T. bas Petced onov 2 neutrinos oscillate ⟺ mν≠0 inThethe this 3-neutrino followingReviewsin . values(2 mixingθ12)=0 are scheme obtained.857 ± described0. through024 in data the review analyses “Neutr basedino on • Mass, Mixing,2 and Oscillations”± by× K.− Nakamura5 2 and S.T. Petcov the 3-neutrino∆m21 mixing=(7. scheme50 0. described20) 10 ineV the review “Neutrino Review2 [i] Mass,in this Mixing,sin .(2 andθ23 Oscillations”) > 0.95 by K. Nakamura and S.T. Petcov in this Review.2 +0.12 × −3 2[j] ∆m32 =(2.32−0.08) 10 eV 2 sin (2θ13)=0.098 ± 0.013 HTTP://PDG.LBL.GOV Page 9 Created: 6/18/2012 15:05 Heavy Neutral Leptons, Searches for Friday, October 12, 12 HTTP://PDG.LBL.GOV Page 9 Created: 6/18/2012 15:05 ForHTTP://PDG.LBL.GOV excited leptons, see Compositeness Page Limits 9 below. Created: 6/18/2012 15:05 Stable Neutral Heavy Lepton Mass Limits Mass m > 45.0GeV,CL=95% (Dirac) Mass m > 39.5GeV,CL=95% (Majorana) Neutral Heavy Lepton Mass Limits Mass m > 90.3GeV,CL=95% (Dirac νL coupling to e, µ, τ;conservativecase(τ)) Mass m > 80.5GeV,CL=95% (Majorana νL coupling to e, µ, τ;conservativecase(τ)) NOTES [a]Thisisthebestlimitforthemodee− → νγ.Thebestlimitfor“electron disappearance” is 6.4 × 1024 yr. [b]Seethe“NoteonMuonDecayParameters”intheµ Particle Listings for definitions and details. [c] Pµ is the longitudinal polarization of the muon from pion decay.In standard V −A theory, Pµ =1andρ = δ =3/4. − [d]Thisonlyincludeseventswiththeγ energy > 10 MeV. Since the e νe νµ − and e νe νµ γ modes cannot be clearly separated, we regard the latter mode as a subset of the former. [e]SeetherelevantParticleListingsfortheenergylimitsused in this mea- surement. [f ]Atestofadditivevs.multiplicativeleptonfamilynumberconservation. [g]Basismodefortheτ. [h] L± mass limit depends on decay assumptions; see the Full Listings. 2 [i]Thelimitquotedcorrespondstotheprojectionontothesin (2θ23)axis 2 − 2 of the 90% CL contour in the sin (2θ23) ∆m32 plane. 2 [j]Thesignof ∆m32 is not known at this time. The range quoted is for the absolute value. HTTP://PDG.LBL.GOV Page 10 Created: 6/18/2012 15:05 Neutrinos oscillate! Friday, October 12, 12 Neutrino oscillations Flavor basis: • 3 neutrino states → 3 masses m1, m2 , m3 ⌫ , ⌫ , ⌫ {| ei | µi | ⌧ i} • States with definite masses (mass eigenstates) in general do not coincide with flavor states Mass basis: ⌫1 , ⌫2 , ⌫3 • Quantum mechanics: {| i | i | i} States with same quantum numbers can mix, as it happens for the quarks d0 d CKM s0 = V s 0 1 0 1 • The mixing matrices V are 3x3 unitary b0 b matrices @ A @ A ‣ CKM = Cabibbo-Kobayashi-Maskawa ⌫e ⌫1 ⌫ = V PMNS ⌫ ‣ PMNS = Pontecorvo; 0 µ1 0 21 Maki-Nakagawa-Sakata ⌫⌧ ⌫3 @ A @ A Friday, October 12, 12 Neutrino oscillations • Consider 2 flavor case: ‣ for simplicity ‣ dominant oscillations are well- described by 2-flavor mixing ⌫ = cos ✓ ⌫ +sin✓ ⌫ • Flavor and mass eigenstates connected | µi | 1i | 2i by a 2x2 rotation matrix ⌫ = sin ✓ ⌫ + cos ✓ ⌫ | ⌧ i − | 1i | 2i Neutrino propagation: νμ created at t=0 with 3-momentum p ⌫(0) = ⌫µ = cos ✓ ⌫1 +sin✓ ⌫2 • | i | i | i | i iE t iE t Neutrino state at time t ⌫(t) = e− 1 cos ✓ ⌫ + e− 2 sin ✓ ⌫ • | i | 1i | 2i Different mass components have different m2 m2 • E = p2 + m2 p + i p + i ]a) energy i i ' 2p ' 2E q Friday, October 12, 12 Neutrino oscillations Oscillation probability: P (⌫ ⌫ ; t)= ⌫ ⌫(t) 2 µ ! ⌧ |h ⌧ | i| iE t iE t 2 = sin ✓ ⌫ + cos ✓ ⌫ e− 1 cos ✓ ⌫ + e− 2 sin ✓ ⌫ |{− h 1| h 2|}{ | 1i | 2i}| 2 2 iE t iE t 2 = cos ✓ sin ✓ e− 2 e− 1 | − | = 2 cos2 ✓ sin2 ✓ 1 cos[(E E )t] { − 2 − 1 } 2 2 2 ∆m 2 2 2 =sin 2✓ sin t ∆m = m2 m1 4E − As function of distance L=c*t=t: ∆m2 P (⌫ ⌫ ; L)=sin2 2✓ sin2 L µ ! ⌧ 4E L/E determines 2 2 2 2 L(km) =sin 2✓ sin 1.27∆m (eV ) sensitivity to E(GeV) 2 Δm Friday, October 12, 12 Neutrino oscillations 3 flavor oscillations: atmospheric solar cross mixing ^J) Friday, October 12, 12 Neutrino state cross-composition ^H) The final 3 flavor mixing scheme" Results inThe the final 33 flavor flavor mixing scheme mixing" scheme Neutrino state cross-composition 58)6%"7&$0$()U)53%&-)HIJH) JH`) ^H) 58)6%"7&$0$()U)53%&-)HIJH) JH`) Discovery of a non-zero angle θ13! Friday, October 12, 12 Leptonic CP violation: δCP ≠ 0? • θ13 ≠ 0 : necessary condition for leptonic CP violation ‣ θ13 = 0: effective 2 flavor mixing ‣ CP violation only with unitary 3x3 matrices (or larger) • Dirac-neutrinos: 1 CP violating phase • Majorana-neutrinos: 2 additional CP violating phases • CP violation in quark sector not sufficient to explain the baryon asymmetry of the universe (BAU) • Leptonic CPV would give an additional contribution Measurement of δCP exciting challenge Friday, October 12, 12 Neutrinos and the Standard Model Friday, October 12, 12 Neutrinos and the Standard Model • Neutrino oscillations: The Standard Model ‣ at least two massive neutrino states ‣ why should neutrinos be massless anyway? Particles Spin SU(3)C SU(2)L U(1)Y (no symmetry) uL 1 1 Q = 2 323 dL 3c 4 1 4 In the original SM, neutrinos are massless uR 2 31 3 • c 1 ≠2 ⇒ oscillation results = physics beyond the SM dR 2 313 ‹L 1 L = 2 12-1 However, massive neutrinos possible by a eL • 3c 4 1 ‹R 2 1 1 0 minimal extension of the SM: c 1 eR 2 112 Φ+ H = 0 1 2 1 ‣ right-handed neutrino Φ0 3– 4 Gµ 1 810 ‣ gauge singlet (“sterile neutrino”) a Wµ 1 130 11 ‣ can be a Dirac fermion like the electron Bµ 1 0 ★ mass term via Yukawa interaction with Higgs boson (Higgs mechanism) 3/20 ★ neutrino masses of order meV: tiny(!) Yukawa couplings Friday, October 12, 12 Neutrinos and the Standard Model • Neutrino oscillations: ‣ at least two massive neutrino statesThe Standard Model ‣ why should neutrinos be massless anyway? (no symmetry) Particles Spin SU(3)C SU(2)L U(1)Y uL 1 1 Q = 2 323 In the original SM, neutrinos are massless dL • 3c 4 1 4 ⇒ oscillation results = physics beyond the SM uR 2 31 3 c 1 ≠2 dR 2 313 Conversely, neutrino only fermion in the SM ‹L 1 • L = 2 12-1 without electric charge: eL 3c 4 1 ‹R 2 1 1 0 0 0 c 1 ‣ can be its own anti-particle (like γ, Z ,π ,η) eR 2 112 Φ+ H