[PPT] - Recent T2K Neutrino Oscillation Results Artur Sztuc PowerPoint Presentation

SLIDE 1

Recent T2K Neutrino Oscillation Results

Artur Sztuc

a.sztuc16@imperial.ac.uk On behalf of the T2K collaboration TAUP 2019

SLIDE 2

Neutrino Mass Mixing

ν3 ν2 ν1

Normal Hierarchy (NH) Inverted Hierarchy (IH)

Flavour eigenstates; νe, νµ

and ντ (interact)

Mass eigenstates; ν1, ν2

and ν3 (propagate) νe

νµ ντ

=

  1 c23 s23 −s23 c23  

atmospheric, beam

  c13 s13e−iδCP 1 −s13eδCP c13  

reactor, beam

  c12 s12 −s12 c12 1  

solar, reactor

ν1

ν2 ν3

sij = sin θij

cij = cos θij Super-K, IceCube, T2K, NOνA, Opera T2K, NOνA, Double Chooz, Daya Bay, RENO Super-K, KamLAND, SNO

Artur Sztuc TAUP, Sep 2019 2

SLIDE 3

The T2K experiment

Around 500 people from 68 institutions, 12 countries
∼0.6 GeV narrow beam from J-PARC (ν and ¯

ν mode)

Near detector; ND280, 280 m from beam target,

measures unoscillated spectrum

Far detector; Super-Kamiokande, 295 km from the ν

source, measures oscillated spectrum

Artur Sztuc TAUP, Sep 2019 3

SLIDE 4

Long baseline oscillations (@T2K)

νµ disappearance

50 100 150 200 250 300

Number of events per bin

Unoscillated Prediction Oscillated with Reactor Constraint Oscillated without Reactor Constraint Data

T2K Run 1-9d Preliminary

1 2 3 4 5 6 7

Reconstructed Neutrino Energy (GeV)

1 2

Ratio

Location of the dip: |∆m2

32| (does not depend on the sign)

Depth of the dip: sin2(θ23)

Difficult to separate θ23 > 45 and θ23 < 45

νe appearance

2 4 6 8 10 12 14 16 18 20

Number of events per bin

Unoscillated Prediction Oscillated with Reactor Constraint Oscillated without Reactor Constraint Data

T2K Run 1-9d Preliminary

0.2 0.4 0.6 0.8 1 1.2

Reconstructed Neutrino Energy (GeV)

10 20

Ratio

Magnitude of the peak; sin2(θ23), sin2(θ13), δCP

Small dependence on the sign of ∆m2

32

Channel for CP violation detection

First-order sensitivity: |∆m2

32|, sin2 θ23, sin2 θ13

Second-order sensitivity: sign of ∆m2

32, sin2 θ23 octant, δCP

Artur Sztuc TAUP, Sep 2019 4

SLIDE 5

The T2K neutrino beam

(GeV)

ν

E

1 2 3

(A.U.)

295km

µ

ν

Φ

0.5 1

° OA 0.0 ° OA 2.0 ° OA 2.5

1 2 3

)

e

ν →

µ

ν P(

0.05 0.1

= 0

CP

δ NH, = 0

CP

δ IH, /2 π =

CP

δ NH, /2 π =

CP

δ IH,

1 2 3

)

µ

ν →

µ

ν P(

0.5 1

= 1.0

23

θ 2

2

sin = 0.1

13

θ 2

2

sin

2

eV

3

10 × = 2.4

32 2

m ∆

Off-axis beam angle tuned for maximal νµ disappearance

𝝃 𝜉̅

The latest result includes combined run 1–9 data

νµ: 1.51 × 1021 POT
¯

νµ: 1.65 × 1021 POT

(POT; Protons on target)

Beam operating near 500kW

Artur Sztuc TAUP, Sep 2019 5

SLIDE 6

T2K near detectors

ND280

Off-axis, 280 m from beam target
Measures unoscillated ν spectrum
Neutrino cross-section measurements

(T2K cross-sections results talk)

INGRID

On-axis, 280 m from beam target
Measures beam direction and stability
Also contributes to cross-sections
Different flux spectrum

Artur Sztuc TAUP, Sep 2019 6

SLIDE 7

Analysis strategy

Oscillation Fit

Oscillation parameters Super-K detector model Flux model

NA61 SHINE Data INGRID/ Beam monitor data

ND280 detector model ND280 Data Cross- section model

External Cross- section data

Super-K data

Artur Sztuc TAUP, Sep 2019 7

SLIDE 8

ND280 Data selection

ND280 data constrains the neutrino flux and cross-section systematics at Super-K Data samples for two FGD targets (CH and H2O);

3×2 samples for ν beam mode
νµCC0π (primary in the analysis)
νµCC1π (shown on right)
CCOther
4×2 samples for ¯

ν beam mode

¯

νµCC1Track

¯

νµCCNTrack

νµCC1Track
νµCCNTrack

H2O samples constrain water interactions at Super-K Two Fine Grid Detectors (FGD), event display shows FGD1 producing µ+ and π−

Data are binned in outgoing µ momentum and angle

Artur Sztuc TAUP, Sep 2019 8

SLIDE 9

ND280 data fit effect

Prefit CC0π

Events/(100 MeV/c)

500 1000 1500 2000 2500

Data CCQE ν CC 2p-2h ν π CC Res 1 ν π CC Coh 1 ν CC Other ν NC modes ν modes ν

mode

ν

Reconstructed muon momentum (MeV/c)

500 1000 1500 2000 2500 3000 3500 4000 4500 5000

Data / Sim.

0.8 0.9 1.0 1.1 1.2

PRELIMINARY

Postfit CC0π

Events/(100 MeV/c)

500 1000 1500 2000 2500

Data CCQE ν CC 2p-2h ν π CC Res 1 ν π CC Coh 1 ν CC Other ν NC modes ν modes ν

mode

ν

Reconstructed muon momentum (MeV/c)

500 1000 1500 2000 2500 3000 3500 4000 4500 5000

Data / Sim.

0.8 0.9 1.0 1.1 1.2

PRELIMINARY

The prediction agrees much better with the data after the

ND280 fit

This is true for all the data samples

Artur Sztuc TAUP, Sep 2019 9

SLIDE 10

ND280 data fit effect

1

10 1 10

0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3

Prior to ND280 constraint After ND280 constraint

Neutrino Energy (GeV) Flux

µ

ν ND280 FHC ND280 νµ beam flux

Super-K event rates systematic errors

Super-K Without With sample ND280 ND280 ν-beam 1-Ring-µ 14.6% 5.1% ν-beam 1-Ring-e 16.9% 8.8% ¯ ν-beam 1-Ring-µ 12.5% 4.5% ¯ ν-beam 1-Ring-e 14.4% 7.1%

Constraining both flux and

cross-section systematics

(See T2K cross-sections results talk by Callum Wilkinson)

The effect is large

← Systematic errors on Super-K

event rates reduced

Artur Sztuc TAUP, Sep 2019 10

SLIDE 11

Super-K Data

¯ ν-beam 1-Ring-e

Neutrino mode 1Re candidates

30 40 50 60 70 80 90 100 110

Antineutrino mode 1Re candidates

8 10 12 14 16 18 20 22 24

0.55 , 0.45 , 0.50 =

23

θ

2

sin

4

/c

2

eV

3

10 × = 2.45

32 2

m ∆

4

/c

2

eV

3

10 × = -2.43

31 2

m ∆ π =

CP

δ /2 π = +

CP

δ = 0

CP

δ /2 π = -

CP

δ Data (stat. errors only)

T2K Run 1-9 preliminary

Sample δCP = −π/2 δCP = 0 δCP = π/2 δCP = π Observed ν-beam 1-Ring-µ 272.4 272.0 272.4 272.8 243 ¯ ν-beam 1-Ring-µ 139.5 139.2 139.5 139.9 140 ν-beam 1-Ring-e 74.4 62.2 50.6 62.7 75 ¯ ν-beam 1-Ring-e 17.1 19.4 21.7 19.3 15 ν-beam 1-Ring-e 7.0 6.1 4.9 5.9 15 + π+ sin2 θ13=0.0212, sin2 θ23=0.528, ∆m2

32=2.51×10−3, rest fixed to 2018 PDG

values

Artur Sztuc TAUP, Sep 2019 11 P-value ∼0.07

SLIDE 12

Appearance results

Both Hierarches NH IH

T2K excludes CP conservation at 2σ
Best-fit δCP, marginalized over both MH, is -1.74 rad
Constraints tighter than in the expected sensitivity
Best-fit sin2(θ13) = 0.0214

Artur Sztuc TAUP, Sep 2019 12

SLIDE 13

Disappearance results

Both Hierarchies NH

Bayes factor of 8.0 for NH/IH
Considered “significant” by the Jeffrey’s scale
NH 8 times more probable than IH
Best-fit sin2(θ23) = 0.537
Best-fit ∆m2

32 = 2.46 × 10−3

Artur Sztuc TAUP, Sep 2019 13

SLIDE 14

Conclusions

CP conserving values (δCP = 0, π) comfortably

excluded at 2σ

Best-fit δCP value: -1.74 rad
Data prefers Normal Hierarchy (∼89%)
Preference for the upper octant of sin2 θ23

(∼80%)

More talks and posters from T2K!

Artur Sztuc TAUP, Sep 2019 14

SLIDE 15

BACKUPS

Artur Sztuc TAUP, Sep 2019 15

SLIDE 16

Beam flux

(GeV)

ν

E 2 4 6 8 10 p.o.t)

21

/50MeV/10

2

Flux (/cm

9

10

11

10

12

10 µ

ν

e

ν

µ

ν

e

ν Neutrino Mode Flux at ND280

(GeV)

ν

E 2 4 6 8 10 p.o.t)

21

/50MeV/10

2

Flux (/cm

3

10

4

10

5

10

6

10 µ

ν

e

ν

µ

ν

e

ν Neutrino Mode Flux at the far detector

(GeV)

ν

E 2 4 6 8 10 p.o.t)

21

/50MeV/10

2

Flux (/cm

8

10

9

10

11

10

12

10 µ

ν

e

ν

µ

ν

e

ν Antineutrino Mode Flux at ND280

(GeV)

ν

E 2 4 6 8 10 p.o.t)

21

/50MeV/10

2

Flux (/cm

2

10

3

10

4

10

5

10

6

10 µ

ν

e

ν

µ

ν

e

ν Antineutrino Mode Flux at the far detector

Beam flux composition at ND280 Beam flux composition at Super-K

Artur Sztuc TAUP, Sep 2019 16

SLIDE 17

Neutrino interactions

Charged Current Quasi Elastic (CCQE)

n W

d d u

p

u d u

l νl

−

Charged Current Resonant Pion (CCRES)

p W

d u u

p

u u u d u u u d

l νl π+ Δ

++ −

Charged Current Deep Inelastic Scattering (CCDIS)

l νl W N N

−

hadrons

CCQE dominant interaction mode for T2K
Interactions with nucleon inside a nucleus
Nuclear model dependent
Nuclear effects can bias interaction mode and

energy reconstruction

Interaction and Nuclear models tuned to

external data

Artur Sztuc TAUP, Sep 2019 17

SLIDE 18

Super-K Data

ν-beam 1-Ring-e

Number of Events

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

Reconstructed Energy (GeV) ν

0.2 0.4 0.6 0.8 1 1.2

(degrees) θ

20 40 60 80 100 120 140 160 180 T2K Run1-9c Preliminary

ν-beam 1-Ring-e + π+

Number of Events

0.02 0.04 0.06 0.08 0.1

Reconstructed Energy (GeV) ν

0.2 0.4 0.6 0.8 1 1.2

(degrees) θ

20 40 60 80 100 120 140 160 180 T2K Run1-9c Preliminary

¯ ν-beam 1-Ring-e

Number of Events

0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18

Reconstructed Energy (GeV) ν

0.2 0.4 0.6 0.8 1 1.2

(degrees) θ

20 40 60 80 100 120 140 160 180 T2K Run1-9c Preliminary

ν-beam 1-Ring-µ

Reconstructed Energy (GeV) ν

0.5 1 1.5 2 2.5 3

Number of Events

5 10 15 20 25 30

e

ν →

µ

ν

e

ν →

µ

ν NC intrinsic

e

ν /

e

ν intrinsic

µ

ν intrinsic

µ

ν

T2K Run1-9c Preliminary

¯ ν-beam 1-Ring-µ

Reconstructed Energy (GeV) ν

0.5 1 1.5 2 2.5 3

Number of Events

2 4 6 8 10 12 14 16

e

ν →

µ

ν

e

ν →

µ

ν NC intrinsic

e

ν /

e

ν intrinsic

µ

ν intrinsic

µ

ν

T2K Run1-9c Preliminary

Artur Sztuc TAUP, Sep 2019 18

SLIDE 19

Super-K Event display

e-like event µ-like event

Super-Kamiokande IV

Run 999999 Sub 0 Event 7 11-11-23:19:16:50 Inner: 2011 hits, 3854 pe Outer: 2 hits, 2 pe Trigger: 0x07 D_wall: 1405.1 cm Evis: 419.0 MeV e-like, p = 419.0 MeV/c Charge(pe) >26.7 23.3-26.7 20.2-23.3 17.3-20.2 14.7-17.3 12.2-14.7 10.0-12.2 8.0-10.0 6.2- 8.0 4.7- 6.2 3.3- 4.7 2.2- 3.3 1.3- 2.2 0.7- 1.3 0.2- 0.7 < 0.2 0 mu-e decays 500 1000 1500 2000 130 260 390 520 650 Times (ns)

Super-Kamiokande IV

Run 999999 Sub 0 Event 18 11-11-21:09:42:21 Inner: 1194 hits, 2267 pe Outer: 3 hits, 2 pe Trigger: 0x07 D_wall: 218.0 cm Evis: 262.3 MeV mu-like, p = 439.9 MeV/c Charge(pe) >26.7 23.3-26.7 20.2-23.3 17.3-20.2 14.7-17.3 12.2-14.7 10.0-12.2 8.0-10.0 6.2- 8.0 4.7- 6.2 3.3- 4.7 2.2- 3.3 1.3- 2.2 0.7- 1.3 0.2- 0.7 < 0.2 1 mu-e decay 500 1000 1500 2000 54 108 162 216 270 Times (ns)

Artur Sztuc TAUP, Sep 2019 19

SLIDE 20

Bi-probability plots: intro

)

e

ν →

µ

ν P(

0.025 0.03 0.035 0.04 0.045 0.05 0.055 0.06 0.065

)

e

ν →

µ

ν P(

0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09

)

2

eV

3

10 × = 2.509

32 2

m ∆ T2K prediction, NH ( )

2

eV

3

10 × = -2.509

32 2

m ∆ T2K prediction, IH (

δCP = +π/2 δCP = -π/2 δCP = 0, ±π

Artur Sztuc TAUP, Sep 2019 20

SLIDE 21

Bi-probability plots

)

e

ν →

µ

ν P(

0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2

)

e

ν →

µ

ν P(

0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2

90% credible interval 68% credible interval β 1--9d free = 1 β 1--9d

0.002 0.004 0.006 0.008 0.01 0.012 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2

)

e

ν →

µ

ν P(

0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2

)

e

ν →

µ

ν P(

NH prediction IH prediction 68% credible interval 90% credible interval

0.0005 0.001 0.0015 0.002 0.0025 0.003 0.0035 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2

)

e

ν →

µ

ν P(

0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2

)

e

ν →

µ

ν P(

NH prediction IH prediction 68% credible interval 90% credible interval

Free β fit probes non-PMNS space
β = 1 fit probes PMNS-only space
Data consistent with the PMNS model

Artur Sztuc TAUP, Sep 2019 21

SLIDE 22

All osc parameters:

with θ13 reactor constraint

Artur Sztuc TAUP, Sep 2019 22

SLIDE 23

All osc parameters:

without θ13 reactor constraint

Artur Sztuc TAUP, Sep 2019 23

SLIDE 24

With/without θ13 reactor

CP

δ

3 − 2 − 1 − 1 2 3

Posterior probability

0.2 0.4 0.6 0.8 1

T2K Run 1-9d Preliminary

woRC wRC

Normal Hierarchy only
Reactor constraint in form
f a prior
Reactor θ13 taken from

2018 PDG

23

θ

2

sin

0.4 0.45 0.5 0.55 0.6 0.65 23 2

M ∆

0.0023 0.0024 0.0025 0.0026 0.0027 0.0028 0.0029

T2K Run 1-9d Preliminary

woRC 90% wRC 90% woRC 68% wRC 68% woRC Best Fit wRC Best Fit

13

θ

2

sin

0.02 0.03 0.04 0.05 0.06 CP

δ

3 − 2 − 1 − 1 2 3

T2K Run 1-9d Preliminary woRC 90% woRC 68% woRC Best Fit wRC 90% wRC 68% wRC Best Fit

Artur Sztuc TAUP, Sep 2019 24

SLIDE 25

Data vs sensitivity

CP

δ

3 − 2 − 1 − 1 2 3

Posterior probability

0.2 0.4 0.6 0.8 1

T2K Run 1-9d Preliminary

Asimov Data

Normal Hierarchy only
Higher constraint on δCP

than expected from the sensitivity

23

θ

2

sin

0.4 0.45 0.5 0.55 0.6 0.65 23 2

M ∆

0.0023 0.0024 0.0025 0.0026 0.0027 0.0028 0.0029

T2K Run 1-9d Preliminary

Asimov 90% Data 90% Asimov 68% Data 68% Asimov Best Fit Data Best Fit

13

θ

2

sin

0.016 0.018 0.02 0.022 0.024 0.026 0.028 0.03 0.032 0.034 CP

δ

3 − 2 − 1 − 1 2 3

T2K Run 1-9d Preliminary Asimov 90% Asimov 68% Asimov Best Fit Data 90% Data 68% Data Best Fit

Artur Sztuc TAUP, Sep 2019 25

SLIDE 26

New vs old results

CP

δ

3 − 2 − 1 − 1 2 3

Posterior probability

0.2 0.4 0.6 0.8 1

T2K Run 1-9d Preliminary

Run 1-9c Run 1-9d

Normal Hierarchy only
With reactor θ13
The reactor θ13 updated

in new fit

23

θ

2

sin

0.4 0.45 0.5 0.55 0.6 0.65 23 2

M ∆

0.0023 0.0024 0.0025 0.0026 0.0027 0.0028 0.0029

T2K Run 1-9d Preliminary

Run 1-9c 90% Run 1-9d 90% Run 1-9c 68% Run 1-9d 68% Run 1-9c Best Fit Run 1-9d Best Fit 13

θ

2

sin

0.016 0.018 0.02 0.022 0.024 0.026 0.028 0.03 0.032 0.034 CP

δ

3 − 2 − 1 − 1 2 3

T2K Run 1-9d Preliminary Run 1-9c 90% Run 1-9c 68% Run 1-9c Best Fit Run 1-9d 90% Run 1-9d 68% Run 1-9d Best Fit

Artur Sztuc TAUP, Sep 2019 26

SLIDE 27

New vs old results

CP

δ

3 − 2 − 1 − 1 2 3

Posterior probability

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

T2K Run 1-9d Preliminary

Run 1-9c Run 1-9d

Normal Hierarchy only
Without reactor θ13

23

θ

2

sin

0.4 0.45 0.5 0.55 0.6 0.65 23 2

M ∆

0.0023 0.0024 0.0025 0.0026 0.0027 0.0028 0.0029

T2K Run 1-9d Preliminary

Run 1-9c 90% Run 1-9d 90% Run 1-9c 68% Run 1-9d 68% Run 1-9c Best Fit Run 1-9d Best Fit 13

θ

2

sin

0.02 0.03 0.04 0.05 0.06 CP

δ

3 − 2 − 1 − 1 2 3

T2K Run 1-9d Preliminary Run 1-9c 90% Run 1-9c 68% Run 1-9c Best Fit Run 1-9d 90% Run 1-9d 68% Run 1-9d Best Fit

Artur Sztuc TAUP, Sep 2019 27