Recent Results in Neutrino Physics Seventh Topical Seminar on The - PowerPoint PPT Presentation

Lucio Ludovici Siena INFN Roma 1 1 th October 2001 Recent Results in Neutrino Physics Seventh Topical Seminar on The Legacy of Lep and SLC Siena 8- 1 1 October 2001

Mass Direct Measurements Direct kinematic limits on m ν x2 = Σ Σ |U xi | 2 m i2 ν e < 2.2 eV (1 ) Mainz Tritium endpoint (eventually m ν 2 >0!) m ν Troitsk experiment 2.5 eV (+ seasonal anomaly ?!) → → ∼ 0.5 eV reachable in future. Criogenic Microcalorimetry ( 1 87 Re), now <26 eV ( → → 1 0 eV ) (Genova, Milano). ) π π→ →µν µν at rest. Limited by the uncertainty 90 keV (1 m ν µ < 1 νµ on the pion mass ( ∆ ∆ m/ m=2.6 . 1 0 - 6 ). Clever idea to reach ∼ 1 0 keV sensitivity using decay in flight at the BNL (g- 2) ring. ) Exploit kinematic correlation Mh,Eh in 5.5 MeV (1 m ν τ < 1 ντ τ τ→ → n π(π π(π o )ν )ν τ τ (Aleph,Cleo,Opal). → → ∼ 3 MeV, Babar, Belle (systematics ?!). ) 95% (1 CL

Double Beta Decay SM 2νββ 2νββ observed with radiochemical inclusive methods. Direct counting experiment search the non- SM 0νββ 0νββ ( ∆ ∆ L=2) 0νββ 0νββ / 2 → → limit on <m ν >= Σ Σ U ei2 m i Physics beyond SM or limit on t 1 90% CL limit <m ν > (eV) <m ν > limited ( ∼ 1 eV) by the 76 Ge Heid.- Moscow 0.40 uncertainty on the nuclear 76 Ge IGEX 0.44 matrix element calculations UCI 82 Se 5.4 Cancellations possible 1 00 Mo ELEGANT 2.7 1 1 6 Cd Kiev- Firenze 3.3 In models with neutrino 1 28 Te mass degeneration → → Missouri 1 .5 constraint on the mixing 1 30 Te Milano 2.6 angles combination Σ Σ U ei2 1 36 Xe Cal.UN.PSI 3.5 1 50 Nd UCI 7.1

Source “ Breaking News” now, <2005, >=2005, sometime/ maybe Sun SNO 2001 SNO, GNO, Super- K, Borexino Atmosphere Super- K 1 998 Super- K, Soudan2, Monolith, UNO Reactors Chooz 1 999 MUNU, Kamland Accelerators K2K 2000 K2K (J HF), MiniBoone, Minos, Opera, Icarus, NuFact Astrophysics Amanda 2000 Baikal, Amanda, Antares, ICECUBE, Km 3

Neutrino from the SUN Chlorine Homestake W ater, D 2 O ν e + 37 Cl → ν → 37 Ar + e - Chlorine Gallium Flux (cm - 2 s - 1 / M eV) Gallium SAGE, Gallex,GNO ν ν e + 71 Ga → → 71 Ge + e - W ater Kamioka, SuperK ν x + e - → ν → ν ν x + e - (ES) D 2 O SNO ν x + e - → ν → ν ν x + e - (ES) ν ν e + d → → p + p + e - (CC) ν ν x + d → → n + p + ν ν x (NC)

The Problem... +1 .3 +0.20 +9 1 29 7.7 1 .0 - 7 - 1 .1 - 0.1 6 75+8 74+7 - 7 - 6 0.54 ± 0.08 0.47 ± 0.02 SuperK 0.35 ± 0.03 2.58 ± 0.23 SNO CC Gallex + Homestake Kamiokande SAGE GNO H 2 O Ga Cl 8 B 7 Be pp, pep CNO experiments

SNO NC (1 :1 ), ES (1 :6.5) : Sensitivity to ν ν µ,τ µ,τ energy flavour CC vs NC (CC vs ES) : direction ν ν e → active is a smoking ν x +e - ν gun (appearance, flux ν e +d → p+p+e - ν ν x +e - →ν ν ν x +d → n+p+ ν ν x independent) NC : Total ν ν flux from 8 B CC ( ∆ E/ E ≈ ≈ 20% ) : MSW spectral distortion, Day/ Night effect, seasonal CC+ES+NC, SNO I, II, III Large potential to explore the parameter space (SMA, LMA, LOW , Vacuum)

Appearance of Active Neutrino (units: 1 in te 8 B Flux +0.1 2 Φ Φ CC ( 8 B) = 1 .75 ± 0.07 ± 0.05 SNO 0 6 cm - 2 s - 1 ) - 0.1 1 SNO (stat) (sist) (teor) +0.1 6 Φ Φ ES ( 8 B) = 2.39 ± 0.34 SNO - 0.1 4 SNO (stat) (sist) Φ Φ ES - Φ Φ CC = 0.64 ± 0.40 .6 σ σ SNO 1 SNO SNO +0.08 Φ ES ( 8 B) = 2.32 ± 0.03 SuperK - 0.07 SK (stat) (sist) Φ ES - Φ Φ Φ CC = 0.57 ± 0.1 3.3 σ σ SNO+SuperK 7 SK SNO Appearance in the solar flux of active neutrino ≠ν ν e Pure ν ν e →ν ν sterile oscillation excluded at more than 3 σ σ

8 B and 7 Be Flux in Chlorine Φ Φ ES ( 8 B) - Φ Φ CC ( 8 B) ⇒ Φ Φ ν τ ( 8 B) = 0.57 ± 0.1 0 6 cm - 2 s - 1 νµ µ + ν ντ 7 . 1 SK SNO 0 6 cm - 2 s - 1 Φ CC ( 8 B) ⇒ Φ Φ Φ ν .75 ± 0.1 ν e ( 8 B) = 1 5 . 1 SNO 37 Cl ( 8 B) = 2.00 ± 0.1 Φ 9 SNU (BP: 5.9 SNU) 37 Cl = 2.56 ± 0.23 SNU Homestake: Φ 37 Cl ( 7 Be+pep+CNO) = 0.56 ± 0.30 SNU Φ (BP: 1 .8 SNU) ± 1 7 Be (+CNO+pep) suppression (31 7% ) is consistent with the 8 B suppression (35 ± 3% ). The 7 Be puzzle is solved.

The Bahcall’s Glory (10 6 /cm 2 /s) BP95B B82 BPB98C BPB01 Φ Φ ACTIVE Filippone, Schramm 82 Turck- Chieze, Lopez 93 Dar 96 Φ ν Φ ν e (10 6 /cm 2 /s) Total 8 B neutrino flux: 0 6 cm - 2 s – 1 5.44 ± 0.99 . 1 Φ ES = Φ Φ Φ ν η . ( Φ Φ ACTIVE - Φ Φ ν / η ν e +1 ν e )

Solar: Present and Future Oscillation Evidence for inclusive appearance of ν ν µ µ , ν ν τ τ in the ν ν e produced in the sun’s thermonuclear reaction ⇒ SNO II, SNO III Standard Solar Model Direct measurement of the active neutrino flux from 8 B confirms calculations (most cited: BPB2001 ). Other components are expected less model dependent, but ... ⇒ GNO (pp), Borexino (pin down 7 Be line) Distorsioni spettrali No evidence. Chlorine and water reconciled ⇒ SNO, Super- K(>6MeV), Borexino (1 - 5MeV) Day/ Night, seasonal variations No evidence. ⇒ GNO, SNO, Borexino Kamland Reactor neutrino could (if LMA) provide the final clue to the long standing solar neutrino problem

KamLAND@ Kamioka Borexino@ LNGS

Atmospheric: zenith Calculations: ∆Φ ∆Φ atm / Φ Φ atm = 20% event i SuperK statistic 79.5 kt . yr Evidence for oscillation: deficit of ν ν µ • 50% µ flux ν e flux as expected ν • Φ up ∼ ½ Φ Φ Φ down ! • Up/ Down = 0.54 ± 0.04 ± 0.01 χ 2min = 1 χ 32.4/ 1 37 dof for ν ν µ µ →ν ν τ τ with up down sin 2 2 θ θ =1 , ∆ ∆ m 2 = 2.4 . 1 0 - 3 eV 2 cos Θ Θ

Atmospheric: up- ward muons ν > ∼ <E> PC events ν > ∼ 1 <E <E 00 GeV Stopping/ Passing through → normalisation

Oscillation Parameters ∆ ∆ m 2 = (1 .3- 5) . 1 0 - 3 eV 2 sin 2 2 θ θ >0.88, 90% CL 99% CL 90% CL 68% CL This is consistent with Soudan2 e Macro (tough it is almost inconsistent with previous, old Kamiokande results....)

τ τ or sterile Neutrino ? Sterile neutrino signature: Allowed regions SuperK 1 - ring FC events • NC disappearance (99% , 90% CL) • Different matter effects P = sin 2 θ θ , L ν ν µ µ →ν ν τ τ P P → P matt = √ ( ζ ζ - cos2 θ θ ) 2 +sin 2 2 θ θ ∆ m 2 , ζ = 2VE ζ ν / ∆ ν µ ν µ →ν ν s ∆ m 2 >0 ∆ Combined analysis of: 1 ) NC enriched multi- ring 2) PC with E vis >5GeV ν µ ν µ →ν ν s 3) Upward muons ∆ m 2 <0 ∆ Direct tau appearance: Excluded regions multi- ring, PC, up- µ µ Multiring excess, π π o (K2K) 90% CL 99% CL Present significance ∼ 2 σ σ

Sterile Neutrino ? No, Thanks? Solar Purely sterile oscillation excluded at 95% CL by absence of Day/ Night effect in SuperK. SNO(+SuperK) evidence for ν e oscillation into active neutrino. ν Atmospheric Maximal mixing ν ν µ µ →ν ν τ τ favoured. Pure ν ν µ µ →ν ν s excluded CL. Subdominant active component: sin 2 θ θ e3 <0.1 at 99% (Chooz). phase) + 2 ∆ ∆ m 2 Three neutrinos : 3x3 matrix (3angles+1 Relatively large mixing with a sterile neutrino are not excluded by present atmospheric and solar data. Models with 3 active + 1 sterile neutrino (3+1 , 2+2) fit present data.

Sterile Neutrino ? May be Final LSND analysis (1 67t mineral oil: Cherenkov+ scintill.) Appearance of ν ν e p → e + n ( → np → d γ γ (2.2MeV)) in a source µ + decay at rest. Consistent ν of 20- 60 MeV ν ν µ µ from µ ν e π + decay in excess seen in 20- 200 MeV ν ν µ µ produced in π flight. Signal 83.3 ± 21 .2 events. Combined fit: P( ν ν µ µ → ν ν e ) = (0.26 ± 0.06 ± 0.04)% NOMAD ν ν µ µ → ν ν e Karmen II at ISIS: no signal seen. 4 events expected. Karmen- LSND combined analysis inconclusive. Nomad ν ν µ µ → ν ν e escluded ∆ ∆ m 2 > ∼ 1 0 eV 2 Miniboone at the Fermilab Booster is called to clarify this issue.

Chorus and Nomad Search for τ τ produced in ν ν τ τ charged current interactions in a ν ν µ µ beam. τ τ lepton signature: CHORUS: nuclear emulsion target → direct detection of the τ τ and its decay NOMAD: drift chamber target → observation through precise kinematic reconstruction (missing Pt, isolation,...) No surprises! Nomad final analysis Chorus → P = 1 0 - 4 Small mixing and large ∆ ∆ m 2 , motivated by once- upon- a- time popular arguments like solar+hierarchy, cosmology. Training ground for future LBL experiments

K2K: First Generation LBL KEK 1 2 GeV Proto- syncrotron 2 protons/ cycle (1 µ µ s/ 2.2 s) 6 . 1 0 1 .1 ν > ∼ 1 Horn focussed W BB <E .3GeV Close detector at 300m: miniSK+SciFi Far detector at 250 Km: SuperK 9 PoT (1 3.9 . 1 0 1 0 20 within 2004)

K2K: Data vs MC (no osc.) ∆ m 2 ∆ ∆ m 2 ∆ ∆ ∆ m 2 Observed No Oscill. 0 - 3 eV 2 0 - 3 eV 2 0 - 3 eV 2 3 . 1 5 . 1 7 . 1 +6.1 63.9 ± 0.0 FC 22.5 kt 44 41 .5 27.4 23.1 - 6.6 38.4 ± 5.5 1 - ring 26 22.3 1 4.1 1 3.1 µ - like µ 34.9 ± 5.5 24 1 9.3 1 1 .6 1 0.7 3.5 ± 1 e- like 2 2.9 2.5 2.4 .4 25.5 ± 4.3 multi- ring 1 8 1 9.3 1 3.3 1 0.0 Main sistematics: Fiducial volume cuts in the close detector Close to Far extrapolation Probability of no oscillation is < 3%

First Energy Spectrum