Recent results from the T2K experiment Kamil Porwit for the T2K Collaboration University of Silesia, Katowice, Poland XVIII International Workshop on Neutrino Telescopes, Venice, 19.03.2019 K. Porwit@NuTelescopes 2019 Recent results from the T2K experiment 1 / 38 Outline 1 Neutrino mixing 2 The T2K Experiment 3 Oscillation analysis method 4 T2K results 5 Future perspectives 6 Summary K. Porwit@NuTelescopes 2019 Recent results from the T2K experiment 2 / 38 Neutrino Mixing Neutrino Oscillations There are three types of neutrinos: νe, νµ, ντ , −6 ν’s are very light: ∼ 4 × 10 me, neutrino of definite flavour is a linear superposition of mass eigenstates: X ∗ |νl i = Uli |νi i i UPMNS = τ 3 −iδ 1 0 0 c13 0 s13e c12 s12 0 0 c s 0 1 0 −s c 0 23 23 12 12 iδ 0 −s23 c23 −s13e 0 c13 0 0 1 e 1 2 µ cij = cos(θij ), sij = sin(θij ) K. Porwit@NuTelescopes 2019 Recent results from the T2K experiment 3 / 38 Neutrino Mixing Oscillation probabilities Probability of flavour change: 2 ! ( ) ( ) ∆m L P(ν− → ν− ) = δ − 4 X Re(U∗ U U U∗ )sin2 ij α β αβ αi αj βi βi 4E i>j 2 ! (−) ∆m L +2 X Im(U∗ U U U∗ )sin2 ij αi αj βi βi 4E i>j δαβ- Kronecker delta, 2 2 2 ∆mij = mi − mj , i, j = 1, 2, 3, α, β = e, µ, τ L - baseline, E - ν energy P(να → νβ) 6= P(¯να → ν¯β) will violate CP invariance! K. Porwit@NuTelescopes 2019 Recent results from the T2K experiment 4 / 38 Neutrino Mixing Long baseline neutrino oscillations Disappearance of νµ/ν¯µ : (−) (−) 2 2 P(νµ → νµ) = 1 − 4cos (θ13)sin (θ23) ! h i ∆m2 L × 1 − cos2(θ )sin2(θ ) sin2 32 13 23 4E + (solar, matter effect terms) 2 location of dip:∆ m32 2 depth of dip: sin (θ23) K. Porwit@NuTelescopes 2019 Recent results from the T2K experiment 5 / 38 Neutrino Mixing Long baseline neutrino oscillations Appearance of νe/ν¯e : (−) (−) P(νµ → νµ) = ! ∆m2 L sin2(θ )sin2(2θ )sin2 32 23 13 4E (+) h 2 2 − sin(2θ12)sin (2θ23)sin (2θ13)cos(θ13) ! ! ∆m2 L ∆m2 L × sin 21 sin2 32 sin(δ ) 4E 4E CP + (CP-even, solar, matter effect terms) magnitude of the peak: 2 2 sin (θ23), sin (2θ13), δCP K. Porwit@NuTelescopes 2019 Recent results from the T2K experiment 6 / 38 Neutrino Mixing Current knowledge of oscillation parameters To understand ν oscillations we need to measure all parameters: ◦ ◦ θ12 = 33.6 ± 0.8 - solar ν’s ◦ ◦ θ23 = 45.6 ± 2.3 - is θ23 maximal? ◦ ◦ θ13 = 8.3 ± 0.2 - recent reactorν ¯e disappearance measurements δCP unknown → possibility of CP violation in the lepton sector mass hierarchy unknown: K. Porwit@NuTelescopes 2019 Recent results from the T2K experiment 7 / 38 The T2K experiment T2K overview ∼500 people from 12 countries, 66 institutes high intensity beam produced at J-PARC with νµ andν ¯µ mode off-axis technique to get narrower energy spectrum main goals: estimate δCP through νe appearance 2 measure θ23, |∆m32|, through νµ disappearance K. Porwit@NuTelescopes 2019 Recent results from the T2K experiment 8 / 38 The T2K experiment Beam production 30 GeV proton beam delivered by Linac→RCS→MR High intensity p+ beam hits the carbon target, magnetic horns focusing outgoing hadrons, ± ± (−) π decays to µ and νµ in 100m long decay volume, beam dump stops almost all µ particles, number of (ν−) ’s is proportional to number of p+ (% beam power ∼ % (ν−) flux) K. Porwit@NuTelescopes 2019 Recent results from the T2K experiment 9 / 38 The T2K experiment Off-axis beam properties narrowed energy spectrum peaks at 0.6GeV νµ flux peaked at maximum disappearance and appearance off-axis technique used in the experiment for the first time K. Porwit@NuTelescopes 2019 Recent results from the T2K experiment 10 / 38 The T2K experiment INGRID On-axis beam detector: 16 modules (iron/scintillator sandwich) additional module with scintillators only count νµ by reconstructing µ from interactions goal: monitor beam rate, direction and stability K. Porwit@NuTelescopes 2019 Recent results from the T2K experiment 11 / 38 The T2K experiment ND280 Off-axis beam detector: sub-detectors in 0.2T field: P0D - π0, TPC - PID, track particles, FGD - target, vertex info., ECAL - PID for particles exiting ND280 (γ’s, π0’s) (ν−) cross-section measurements (−) measure νe contamination in the beam goal: measure (ν−) event spectrum before oscillation occurs K. Porwit@NuTelescopes 2019 Recent results from the T2K experiment 12 / 38 The T2K experiment Far detector - Super-Kamiokande SK far detector: ∼ 1km of screening rocks (2700 meter water equivalent) 50kt water Cherenkov technology > 11000 PMT’s excellent e/µ separation goal: measure (ν−) event spectrum after oscillations occured K. Porwit@NuTelescopes 2019 Recent results from the T2K experiment 13 / 38 The T2K experiment νµ disappearance signal νe appearance signal (µ-like) (e-like) K. Porwit@NuTelescopes 2019 Recent results from the T2K experiment 14 / 38 The T2K experiment T2K Data-Taking status 3.16 × 1021 Protons On Target (POT) latest oscillation results based on: 3.13 × 1021 =∼ 1.49 × 1021ν+ ∼ 1.63 × 1021ν¯ POT 40% of the total approved T2K statistics (7.8 × 1021 POT) K. Porwit@NuTelescopes 2019 Recent results from the T2K experiment 15 / 38 Oscillation analysis method Oscillation Analysis method Number of ν events observed: Eν bins flavours far X X far far far far N = Pνj →νk φj σk Mdet i j Eν bins flavours near X X near near near near N = φj σk Mdet i j compare observed rates at far detector constrain by observed rates at near detector depends on: Oscillation probabilities Neutrino flux Neutrino interaction cross section detection efficiency detector resolution K. Porwit@NuTelescopes 2019 Recent results from the T2K experiment 16 / 38 Oscillation analysis method Oscillation Analysis method NA61/SHINE data ν flux ND280 data model INGRID/Beam ND280 model monitor data ND280 fit External cross section data ν cross SK data section model ν oscillation SK model Oscillation fit model Oscillation parameters K. Porwit@NuTelescopes 2019 Recent results from the T2K experiment 17 / 38 Oscillation analysis method T2K flux prediction Predicted fluxes at SK: Simulations takes into account: hadron interactions: simulated by: Fluka + GEANT3 tuned to: NA61/SHINE data beam parameters horns parameters Largest uncertainties comes from: hadron interactions p+ beam profile + off-axis angle Analysis improvements to include NA61/SHINE replica target data will significantly reduce hadron interaction errors K. Porwit@NuTelescopes 2019 Recent results from the T2K experiment 18 / 38 Oscillation analysis method Oscillation Analysis method NA61/SHINE data ν flux ND280 data model INGRID/Beam ND280 model monitor data ND280 fit External cross section data ν cross SK data section model ν oscillation SK model Oscillation fit model Oscillation parameters K. Porwit@NuTelescopes 2019 Recent results from the T2K experiment 19 / 38 Oscillation analysis method Neutrino Cross Section Model Main interaction at T2K ν energy is Charged Current Quasi-Elastic (CCQE): − νµ + n → µ + p can reconstruct Eν using: m, E, ~p, θµ Charged Current single pion (CC1π): − + νµ + n/p → µ + π + n/p Neutral Current (NC) and Deep Inelastic Scattering (DIS) can be additional backgrounds K. Porwit@NuTelescopes 2019 Recent results from the T2K experiment 20 / 38 Oscillation analysis method Oscillation Analysis method NA61/SHINE data ν flux ND280 data model INGRID/Beam ND280 model monitor data ND280 fit External cross section data ν cross SK data section model ν oscillation SK model Oscillation fit model Oscillation parameters K. Porwit@NuTelescopes 2019 Recent results from the T2K experiment 21 / 38 Oscillation analysis method ND280 role Multiple data samples in ND280 are fitted to constrain the combination of flux and ν interaction systematics at SK 2 × 3 samples (C + H2O) for ν mode: νµCC0π, νµCC1π, CCOther 2 × 4 samples (C + H2O) forν ¯µ mode: ν¯µCC1Track, ν¯µCCNTrack, νµCC1Track, νµCCNTrack Data on carbon and oxygen targets are binned in outgoing µ momentum and angle K. Porwit@NuTelescopes 2019 Recent results from the T2K experiment 22 / 38 Oscillation analysis method ND280 fit Before analysis: After analysis: Data/Sim. ratio is closer to one after fit result of data fit reduces interaction and flux model uncertainties! Errors on SK reduced from: ∼ 15% to ∼ 5% K. Porwit@NuTelescopes 2019 Recent results from the T2K experiment 23 / 38 Oscillation analysis method Oscillation Analysis method NA61/SHINE data ν flux ND280 data model INGRID/Beam ND280 model monitor data ND280 fit External cross section data ν cross SK data section model ν oscillation SK model Oscillation fit model Oscillation parameters K. Porwit@NuTelescopes 2019 Recent results from the T2K experiment 24 / 38 Oscillation analysis method SK data sample with fit 1-r CCQE-µ-like 1-r CCQE-e-like 1-r CC1π+-e-like ν MC assumption: ν¯ δCP = −π/2 Normal Hierarchy 2 sin (θ23) = 0.528 2 sin (θ13) = 0.0219 Fit is done simultaneously to all five data samples K. Porwit@NuTelescopes 2019 Recent results from the T2K experiment 25 / 38 Oscillation analysis method Oscillation Analysis method NA61/SHINE data ν flux ND280 data model INGRID/Beam ND280 model monitor data ND280 fit External cross section data ν cross SK data section model ν oscillation SK model Oscillation fit model Oscillation parameters K. Porwit@NuTelescopes 2019 Recent results from the T2K experiment 26 / 38 T2K results New T2Kν ¯e appearance result Compare consistency with PMNSν ¯e appearance (β=1) and no ν¯e 0 appearance (β=0): P (¯νµ → ν¯e) = β × P(¯νµ → ν¯e) Rate analysis: expected number ofν ¯e events with oscillation (β = 1, 17.2 events) expected number ofν ¯e events without oscillation (β = 0, 9.4 events) data agrees with both hypotheses result is not statistically conclusive - need more data K.