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Neutrino Shadow Play
Xianguo LU/ 卢显国 University of OxfordHEP Seminar, UCAS
Beijing, 7 September 2017
皮影 Shadow playSource: http://www.cnhubei.com/ztmjys-pyts
2
Outline
1. Understanding matter-antimatter asymmetry with neutrinos
2. Nuclear effects in neutrino-nucleus interactions
3. Measuring neutrino interactions
4. A neutrino shadow play
Act One: Neutrino energy independent measurement of nuclear effects
Act Two: Nuclear effect independent measurement of neutrino energy spectra
5. Summary
3
planetxnews.com
NASA /WMAP
Matter-antimatter symmetric
Cosmic Microwave
Early Universe
“Present”Time
4
Matter-antimatter asymmetric
Cosmic Microwave Background
Early Universe
“Present”Time
NASA /WMAP
planetxnews.com
5NASA-HQ-GRIN NGC 4414
Material World Antimaterial World
Matter-antimatter asymmetric
Early Universe
“Present”Time
planetxnews.com
6
Matter-antimatter asymmetricSakharov Conditions:Sakharov Conditions:Baryon number violationC- and CP-symmetry Violation (CPV)Interactions out of thermal equilibrium
Early Universe
Material World Antimaterial World“Present”
Time
NASA-HQ-GRIN NGC 4414
planetxnews.com
7
Matter-antimatter asymmetricSakharov Conditions:Baryon number violationC- and CP-symmetry Violation (CPV)Interactions out of thermal equilibrium
Early Universe
Material World
p
n
“Present”Time
NASA-HQ-GRIN NGC 4414
By Rainer Klute/Arpad Horvath/MissMJ FNAL
planetxnews.com
8
n
p
By Rainer Klute/Arpad Horvath/MissMJ FNAL
9
n
p
Quarkonic CPV insufficient
Leptonic CPV (LCPV) unknown
By Rainer Klute/Arpad Horvath/MissMJ FNAL
10
νµ ν
µ
νµ ν
µ
νµ ν
µ
νµ ν
e
νµ ν
e
νµ ν
µ
νµ ν
µ
νµ ν
µ
νµ ν
e
νµ ν
e
Leptonic CP Symmetry
νµ ν
µ
νµ ν
µ
νµ ν
µ
νµ ν
µ
νµ ν
e
νµ ν
µ
νµ ν
µ
νµ ν
e
νµ ν
e
νµ ν
e
LCPV
Material World Antimaterial World
*no matter effect
11
Material World Antimaterial World
Accelerator
Detector
Rev.Mod.Phys. 84 (2012) 1307
νµ ν
eν
µ ν
e
12
Neutrino Oscillations
PMNS matrixPontecorvo–Maki–Nakagawa–Sakata
13
Neutrino Oscillations
PMNS matrix
θij ≠ 0, δ
CP-phase irreducible → leptonic CP violation
14
Neutrino Oscillations
PMNS matrix
θij ≠ 0, δ
CP-phase irreducible → leptonic CP violation
With a νµ beam
“CP-odd term” in appearance channels allow extraction of δCP
using
neutrino and anti-neutrino beams, up to ±30% effect at T2K – unique opportunities with accelerator neutrinos
Neutrino (flavor) oscillations depend on mixing angles, δCP
-phase and mass differences.
PMNS matrix
* neglecting matter effects
15
Neutrino Oscillations
PMNS matrix
θij ≠ 0, δ
CP-phase irreducible → leptonic CP violation
With a νµ beam
Neutrino (flavor) oscillations depend on mixing angles, δCP
-phase and mass differences.
PMNS matrix
CP-odd term in appearance channels allow extraction of δCP
using neutrino
and anti-neutrino beams, up to ±30% effect at T2K – unique opportunities with accelerator neutrinos
by CPT symmetry
flip sign
* neglecting matter effects
16
Neutrino Oscillations
PMNS matrix
θij ≠ 0, δ
CP-phase irreducible → leptonic CP violation
With a νµ beam
Neutrino (flavor) oscillations depend on mixing angles, δCP
-phase and mass differences.
PMNS matrix
flip sign
by CPT symmetry
CP-odd term in appearance channels allow extraction of δCP
using neutrino
and anti-neutrino beams, up to ±30% effect at T2K – unique opportunities for experiments with accelerator neutrinos
solar + KamLAND et al.
* neglecting matter effects
17
The T2K Experiment
Diagram by Kirsty Duffy
Japan Proton Accelerator Research
Complex (J-PARC)
18
The T2K Experiment
Charge selection on neutrino parents → ν or ν mode
Phys.Rev.Lett. 116 (2016) no.18, 181801
Diagram by Kirsty Duffy
Japan Proton Accelerator Research
Complex (J-PARC)
19
BEAM
Crossed arrays of 9-ton iron-scintillator detectors ➔ Monitor neutrino beam stability and beam spatial
profile➔ estimate beam flux uncertainty➔ stand-alone cross-section measurements
The T2K Experiment
BEAM
Diagram by Kirsty Duffy
Japan Proton Accelerator Research
Complex (J-PARC)
20
The T2K Experiment
Diagram by Kirsty Duffy
Japan Proton Accelerator Research
Complex (J-PARC)
Off-axis (OA) 2.5º
BEAMOff-axis neutrino beams:Reduce dependence on pion energy → narrow-band
Spectrum peak at maximum disappearance @SK
Phys.Rev. D87 (2013) no.1, 012001
21
Off-axisbeam
Dipole magnet (0.2T)
T2K off-axis near detector (ND280)
22
TPC
TPC
TPC
FGD1
FGD2
Tracker:● FGD: Fine-Grained Detector
1. plastic scintillator C8H
8
target 2. C
8H
8 + H
2O target
● Time Projection Chamber (TPC)
● constrain beam flux and cross
section for oscillation analysis● stand-alone neutrino
interaction measurements
T2K off-axis near detector (ND280)
23
Source: http://www-sk.icrr.u-tokyo.ac.jp/sk/detector/image-e.html
T2K far detector:Super-Kamiokande
● 50 kt water-Cherenkov● 11129 20-inch PMTs in inner
detector; 1885 8-inch PMTs in outer veto detector→ time and amplitude of Cherenkov light
µ, e identification→ detect propagated ν from J-PARC→ E
ν rec. from µ/e kinematics
24
Source: http://www.ps.uci.edu/~tomba/sk/tscan/th
e±µ±
● 50 kt water-Cherenkov● 11129 20-inch PMTs in inner
detector; 1885 8-inch PMTs in outer veto detector
T2K far detector:Super-Kamiokande
µ, e identification→ detect propagated ν from J-PARC via time and amplitude of Cher. light→ E
ν rec. from µ/e kinematics
N N'
µ-/µ+/e/e+νµ/ν
µ/ν
e/ν
e
W
Charged-Current Quasi-Elastic(CCQE)
25
SK event reconstruction
NEW since 2016 summer:New reconstruction algorithm: fiTQun (likelihood-based)Re-optimizing fiducial volume: ~30% increase in effective statistics
26
SK event reconstruction
Minimum distance to wall
Distance to wall alongparticle trajectory
NEW since 2016 summer:New reconstruction algorithm: fiTQun (likelihood-based)Re-optimizing fiducial volume: ~30% increase in effective statistics
27
SK event reconstruction
Old FV
New FV
● Larger Towall = finer sampling of ring = better reconstruction● Optimize cuts accounting for statistical and systematic errors
NEW since 2016 summer:New reconstruction algorithm: fiTQun (likelihood-based)Re-optimizing fiducial volume: ~30% increase in effective statistics
28
Data collection history(Protons-On-Target)
29
Data collection history
start of ν-mode
(Protons-On-Target)
30
Data collection history
start of ν-mode
Published resultsPhys. Rev. Lett. 118 (2017) no.15, 151801POT: 7.5×1020 ν, 7.5×1020 ν
(Protons-On-Target)
31
Data collection history
start of ν-mode
Published resultsPhys. Rev. Lett. 118 (2017) no.15, 151801POT: 7.5×1020 ν, 7.5×1020 ν
Stable beam power at 470 kW, doubling ν POT in 1 year (NEW)This talk: 14.7×1020 ν, 7.6×1020 ν, totaling 29% of approved
(Protons-On-Target)
32
ν-mode FGD1 pµ
Near Detector Samples
µ− CC0π µ− CCNπµ− CC1π
µ+ 1-track
µ− 1-track µ− N-track
µ+ N-track
ν-mode FGD1 pµ
● Data➔ 6 ν-mode samples (FGD1,2)➔ 8 ν-mode samples (FGD1,2)
● Model➔ Flux prediction: beamline
MC tuned with ext. data (NA61) + beam monitor, INGRID
➔ Cross-section models tuned to ext. measurements.
33
ν-mode FGD1 pµ
Near Detector Fit – post-fitν-mode FGD1 pµ
● Data➔ 6 ν-mode samples (FGD1,2)➔ 8 ν-mode samples (FGD1,2)
● Simultaneous fit of pµ, θ
µ➔ Data well reproduced:
p-value 0.47➔ Fitted flux parameters near
nominal, most within 1σ prior uncertainty
➔ Nucleon correlations (NEW): 2p2h, RPA effects significantly adjusted
➔ flux × cross section at SK sys. error 13% → 3 %.
µ− CC0π µ− CCNπµ− CC1π
µ+ 1-track
µ− 1-track µ− N-track
µ+ N-track
34
240 νµ
74 νe
15 νe
68 νµ
7 νe
Event distributions and oscillation fit
CC1π+ sampleCCQE-like sample
● Reconstructed neutrino energy distributions at Super-Kamiokande➢ Dotted: data; histogram: oscillation fit results, p-value 0.42
N ∆
eνe
W
CC1π+ via ∆ production
(No CC1π– sample due to π– absorption)
35
240 νµ
74 νe
15 νe
68 νµ
7 νe
Event distributions and oscillation fit
CC1π+ sampleCCQE-like sample
● νµ rate lower than fit, consistent with uncertainties.
N ∆
eνe
W
CC1π+ via ∆ production
(No CC1π– sample due to π– absorption)
36
240 νµ
74 νe
15 νe
68 νµ
7 νe
Event distributions and oscillation fit
CC1π+ sampleCCQE-like sample
● CC1π νe rate: 15 events observed vs. 6.92 maximum prediction
● P-value 0.12 for upward or downward fluctuation in at least 1 of 5 samples
N ∆
eνe
W
CC1π+ via ∆ production
(No CC1π– sample due to π– absorption)
37
Atmospheric parameter constraints
● Fit normal and inverted hierarchies separately● Final systematics pending, possible additional contribution from interaction
models (no significant impact on δCP
)
Final systematics pendingT2K + reactor (PDG16)
38
T2K only T2K + reactor (PDG16)
scale
● Left: T2K best-fit result and confidence intervals compared to PDG 2016: consistent➢ ν data bring in δ
CP-sensitivity
● Right: T2K results with reactor constraint (PDG 2016), contour range much reduced.
Appearance parameter constraints
39
Measurement of δCP
CCQE-like νe and ν
e rate compared to δ
CP=0 predictions:
➢ Excess in neutrino (top)➢ Deficit in antineutrino (bottom)
74 νe
7 νe
40
Measurement of δCP
SK detector
SK FSI+SI+PN
ND280 constrained flux & xsec
σ(νe)/σ(ν
e) NC1γ NC
otherOscillationparameter variation
Total systematic
error
1.60 1.57 2.50 3.03 1.49 0.18 0.79 4.85
Percentage errors on predicted event rate ratio between νe and ν
e samples:
relevant for δCP
extraction
41
Measurement of δCP
SK detector
SK FSI+SI+PN
ND280 constrained flux & xsec
σ(νe)/σ(ν
e) NC1γ NC
otherOscillationparameter variation
Total systematic
error
1.60 1.57 2.50 3.03 1.49 0.18 0.79 4.85
Percentage errors on predicted event rate ratio between νe and ν
e samples:
relevant for δCP
extraction
ND280 constraint on flux & cross section, reducing error from 13% to 3%.
42
Measurement of δCP
SK detector
SK FSI+SI+PN
ND280 constrained flux & xsec
σ(νe)/σ(ν
e) NC1γ NC
otherOscillationparameter variation
Total systematic
error
1.60 1.57 2.50 3.03 1.49 0.18 0.79 4.85
Percentage errors on predicted event rate ratio between νe and ν
e samples:
relevant for δCP
extraction
ND280 constraint on flux & cross section, reducing error from 13% to 3%.
Don’t precisely measure σ(νe) and σ(ν
e) in ND280. Apply a theoretically motivated
error based on Phys.Rev. D86 (2012) 053003.
43
Measurement of δCP
SK detector
SK FSI+SI+PN
ND280 constrained flux & xsec
σ(νe)/σ(ν
e) NC1γ NC
otherOscillationparameter variation
Total systematic
error
1.60 1.57 2.50 3.03 1.49 0.18 0.79 4.85
Percentage errors on predicted event rate ratio between νe and ν
e samples:
relevant for δCP
extraction
ND280 constraint on flux & cross section, reducing error from 13% to 3%.
Don’t precisely measure σ(νe) and σ(ν
e) in ND280. Apply a theoretically motivated
error based on Phys.Rev. D86 (2012) 053003.
Neutral current (NC) interactions not constrained by ND280. Theoretical models constrained by external measurements.
44
Measurement of δCP
SK detector
SK FSI+SI+PN
ND280 constrained flux & xsec
σ(νe)/σ(ν
e) NC1γ NC
otherOscillationparameter variation
Total systematic
error
1.60 1.57 2.50 3.03 1.49 0.18 0.79 4.85
ND280 constraint on flux & cross section, reducing error from 13% to 3%.
Don’t precisely measure σ(νe) and σ(ν
e) in ND280. Apply a theoretically motivated
error based on Phys.Rev. D86 (2012) 053003.
Neutral current (NC) interactions not constrained by ND280. Theoretical models constrained by external measurements.
Total error 4.85% on event rate ratio νe / ν
e (10% by design).
Percentage errors on predicted event rate ratio between νe and ν
e samples:
relevant for δCP
extraction
45
Measurement of δCP
T2K + reactor (PDG16)
2σ CLIntervals
Best fit point: -1.83 radians in Normal Hierarchy2σ CL interval:
Normal Hierarchy: [-2.98, -0.60] radiansInverted Hierarchy: [-1.54, -1.19] radians
CP conserving values 0, π both fall outside 2σ CL intervals
46
arXiv:1609.04111
sys. imprtNormal MH: unknown
δCP
= -π/2
arXiv:1609.04111
Normal MH: unknown
● Extension of T2K run to 20×1021 POT (~2026)● Currently approved for 7.8×1021 POT (~2021) ● Accelerator and beam-line upgrades to 1.3 MW
3-σ sensitivity for CP violation for favorable parameters, if✔ Full T2K-II exposure 20×1021 POT ✔ 50% improvement in effective statistics: horn
current, SK event reconstruction ✔ Systematic uncertainties down to 2/3 of current
size: ND upgrade
arXiv:1609.04111
T2K-II
47
Outline
1. Understanding matter-antimatter asymmetry with neutrinos
2. Nuclear effects in neutrino-nucleus interactions
3. Measuring neutrino interactions
4. A neutrino shadow play
Act One: Neutrino energy independent measurement of nuclear effects
Act Two: Nuclear effect independent measurement of neutrino energy spectra
5. Summary
48
static nucleon target
49
Quasi-elastic scattering (QE)
charged current (CC) ν → l'
quasi-elastic (QE) N → N'
static nucleon target
N N'
µ-/µ+/e/e+νµ/ν
µ/ν
e/ν
e
W
Charged-Current Quasi-Elastic(CCQE)
50
nuclear target(bound nucleon)
Fermi motion (FM) biases Eν reconstruction
51
Fermi motion (FM) biases Eν reconstruction
Multinucleon correlations: cross section unknown, strong bias to all final-state kinematics
Science 320 (2008) 1476-1478
initial correlation large relative motion
52
Science 320 (2008) 1476-1478
initial correlation large relative motion
nuclear target(bound nucleons)
Fermi motion (FM) biases Eν reconstruction
Multinucleon correlations: cross section unknown, strong bias to all final-state kinematics
● Impulse approximation: independent particles● In particle-hole excitation:
➔ RPA (random phase approximation): sum of 1p1h excitation (over all pairs) ~ ground state correlations (long range)
➔ npnh (n≥2): sub-leading terms in ph expansion ~ multinucleon correlations (short range)
53
Resonance production (RES)
nuclear target
charged current (CC) ν → l'
QE-like N → N'including resonance production (RES) ∆ → N'π followed by π absorption
Fermi motion (FM) biases Eν reconstruction
Multinucleon correlations: cross section unknown, strong bias to all final-state kinematicsQE-like: π absorbed in nucleus ← final-state interaction (FSI)
N ∆
eνe
W
CC1π+ via ∆ production
54
nuclear emission
nuclear target
charged current (CC) ν → l'
Fermi motion (FM) biases Eν reconstruction
Multinucleon correlations: cross section unknown, strong bias to all final-state kinematicsQE-like: π absorbed in nucleus ← final-state interaction (FSI)FSI → energy-momentum transferred in nucleus, possible nuclear emission
QE-like N → N'including resonance production (RES) ∆ → N'π followed by π absorption
55nuclear effects
quasielastic– binding energy
– Fermi motion
– Final-state interactions
– multinucleon correlations
Neutrino energy
56
interaction dynamics
nuclear effects
– quasielastic
– resonant
– DIS– binding energy
– Fermi motion
– Final-state interactions
– multinucleon correlations
Neutrino energy
57
interaction dynamics
nuclear effects
nuclear targets
– quasielastic
– resonant
– DIS– binding energy
– Fermi motion
– Final-state interactions
– C
– O
– Fe
– Pb
– Ar
– multinucleon correlations
Neutrino energy
58
interaction dynamics
nuclear effects
nuclear targets
– quasielastic
– resonant
– DIS– binding energy
– Fermi motion
– Final-state interactions
– C
– O
– Fe
– Pb
– Ar
– multinucleon correlations
Neutrino energy
T2K, arXiv:1701.00432
59
interaction dynamics
nuclear effects
nuclear targets
– quasielastic
– resonant
– DIS– binding energy
– Fermi motion
– Final-state interactions
– C
– O
– Fe
– Pb
– Ar
– multinucleon correlations
Neutrino energy
T2K, arXiv:1701.00432
60
interaction dynamics
nuclear effects
nuclear targets
– quasielastic
– resonant
– DIS– binding energy
– Fermi motion
– Final-state interactions
– C
– O
– Fe
– Pb
– Ar
– multinucleon correlations
Neutrino energy
T2K, arXiv:1701.00432
61
Outline
1. Understanding matter-antimatter asymmetry with neutrinos
2. Nuclear effects in neutrino-nucleus interactions
3. Measuring neutrino interactions
4. A neutrino shadow play
Act One: Neutrino energy independent measurement of nuclear effects
Act Two: Nuclear effect independent measurement of neutrino energy spectra
5. Summary
62Source: http://vmsstreamer1.fnal.gov/VMS_Site_03/VMSFlash/090924Minerva/index.htm
MINERvA
63
Nucl.Instrum.Meth. A743 (2014) 130-159
Scintillator trackerCharged lepton: seenProton: track
MINERvA
64
Nucl.Instrum.Meth. 676 (2012) 44-49, Nucl.Instrum.Meth. A743 (2014) 130-159
Scintillator tracker:Charged lepton: full kinematicsProton: full kinematics (full acceptance)
MINERvA
65
Outline
1. Understanding matter-antimatter asymmetry with neutrinos
2. Nuclear effects in neutrino-nucleus interactions
3. Measuring neutrino interactions
4. A neutrino shadow play
Act One: Neutrino energy independent measurement of nuclear effects
Act Two: Nuclear effect independent measurement of neutrino energy spectra
5. Summary
66
interaction dynamics
nuclear effects
nuclear targets
– quasielastic
– resonant
– DIS– binding energy
– Fermi motion
– Final-state interactions
– C
– O
– Fe
– Pb
– Ar
– multinucleon correlations
Neutrino energy X
References: Phys.Rev. C94 (2016) no.1, 015503arXiv:1602.06730arXiv:1606.04403
67
Transverse kinematic imbalances– a neutrino shadow play
68
Source: http://zhejiangpiying.sokutu.com/tupian.html
To make Neutrino Shadow Play, we need ✔ beam of light✔ screen
Transverse kinematic imbalances– a neutrino shadow play
69
To make Neutrino Shadow Play, we need ✔ beam of light → accelerator✔ screen
Source: http://zhejiangpiying.sokutu.com/tupian.html
Transverse kinematic imbalances– a neutrino shadow play
70
To make Neutrino Shadow Play, we need ✔ beam of light → accelerator✔ screen → transverse plane
Source: http://zhejiangpiying.sokutu.com/tupian.html
Transverse kinematic imbalances– a neutrino shadow play
71
To make Neutrino Shadow Play, we need ✔ beam of light → accelerator✔ screen → transverse plane
Static nucleon target
Source: http://zhejiangpiying.sokutu.com/tupian.html
Transverse kinematic imbalances– a neutrino shadow play
72
To make Neutrino Shadow Play, we need ✔ beam of light → accelerator✔ screen → transverse plane
Source: http://zhejiangpiying.sokutu.com/tupian.html
Nuclear target
Transverse kinematic imbalances– a neutrino shadow play
73
To make Neutrino Shadow Play, we need ✔ beam of light → accelerator✔ screen → transverse plane
Nuclear target
Source: http://zhejiangpiying.sokutu.com/tupian.html
Transverse kinematic imbalances– a neutrino shadow play
74
Nuclear targetStatic nucleon target
Transverse kinematic imbalances– a neutrino shadow play
75
● In given acceptance, overall spectral shapes not sensitive to FSIs.● Nuclear effects difficult to observe on top of neutrino-nucleon kinematics.
[arXiv:1608.04655]
MINERvA measurement of single-transverse kinematic imbalances
76
Total Solar eclipse 1999 in FranceBy Luc Viatour
77
● More sensitive to FSIs due to cancellation of nucleon level physics using kinematic imbalances
● Sensitivity achieved by dedicated momentum cuts and corrections.
[arXiv:1608.04655]
MINERvA measurement of single-transverse kinematic imbalances
78
Transverse Fermi motion
(transverse projected) momentum transfer in● initial-state multinucleon correlation, and● final-state interaction
T2K measurement of single-transverse kinematic imbalancesPreliminary, Progress reports:
arXiv:1605.00179, 1610.05077
79
Transverse Fermi motion
(transverse projected) momentum transfer in● initial-state multinucleon correlation, and● final-state interaction
Preliminary, Progress reports: arXiv:1605.00179, 1610.05077
T2K measurement of single-transverse kinematic imbalances
80
Fermi motion: flat
Preliminary, Progress reports: arXiv:1605.00179, 1610.05077
T2K measurement of single-transverse kinematic imbalances
81
Transversely “accelerated” or “decelerated”
“acceleration”
FSI dynamics
Preliminary, Progress reports: arXiv:1605.00179, 1610.05077
T2K measurement of single-transverse kinematic imbalances
82
“deceleration”“acceleration”
Transversely “accelerated” or “decelerated”
FSI dynamics
Preliminary, Progress reports: arXiv:1605.00179, 1610.05077
T2K measurement of single-transverse kinematic imbalances
83
√
Transversely “accelerated” or “decelerated”
FSI dynamics
“deceleration”
Preliminary, Progress reports: arXiv:1605.00179, 1610.05077
T2K measurement of single-transverse kinematic imbalances
84
● Large discrepancy between NEUT and GENIE➢ not seen in single-particle kinematics.
● Highlighted GENIE features (“collinear
enhancement”) all originate from its FSI model, see discussions in [Phys.Rev. C94 (2016) no.1, 015503]:
“the GENIE Collaboration suggested to investigate the effect of the elastic interaction of the hA FSI model.”
Preliminary, Progress reports: arXiv:1605.00179, 1610.05077
T2K measurement of single-transverse kinematic imbalances
85
Outline
1. Understanding matter-antimatter asymmetry with neutrinos
2. Nuclear effects in neutrino-nucleus interactions
3. Measuring neutrino interactions
4. A neutrino shadow play
Act One: Neutrino energy independent measurement of nuclear effects
Act Two: Nuclear effect independent measurement of neutrino energy spectra
5. Summary
86
interaction dynamics
nuclear effects
nuclear targets
– quasielastic
– resonant
– DIS– binding energy
– Fermi motion
– Final-state interactions
– C
– O
– Fe
– Pb
– Ar
– multinucleon correlations
Neutrino energy
X
87
interaction dynamics
nuclear effects
nuclear targets
– quasielastic
– resonant
– DIS– binding energy
– Fermi motion
– Final-state interactions
– C
– O
– Fe
– Pb
– Ar
– multinucleon correlations
Neutrino energy
References: Phys.Rev. D92 (2015) no.5, 051302arXiv:1512.09042arXiv:1606.04403
H
With target,
Eν ∑ final-state energy.
A problem of .
=≠
Hnuclear
detector resolutionnuclear phy. + d.r.
88
● Pure hydrogen
– Technical requirement:
● bubble chamber (historical: 73, 79, 78, 82, 86)
– Safety issue: explosive
● “Since the use of a liquid H2 bubble chamber is excluded in the ND hall due to safety concerns, ...” [FERMILAB-PUB-14-022]
● In the last ~30 years there has been no new measurement of neutrino interactions on pure hydrogen.
Chin. Phys. C 38, 090001 (2014)
H2
89
Lepton-proton interaction → 3 charged particles: l p → l' X Y– Leading order realization in standard model:
Double-Transverse kinematic imbalance
90
Lepton-proton interaction → 3 charged particles: l p → l' X Y– Leading order realization in standard model:
Double-Transverse kinematic imbalance
91
Lepton-proton interaction → 3 charged particles: l p → l' X Y– Leading order realization in standard model:
Double-Transverse kinematic imbalance
92
Lepton-proton interaction → 3 charged particles: l p → l' X Y– Leading order realization in standard model:
Double-Transverse kinematic imbalance
93
Double-transverse momentum imbalance δpTT
● H: 0 ● Heavier nuclei: irreducible symmetric broadening
● by Fermi motion O(200 MeV)● further by FSI
● Hydrogen shape is only detector smearing. ● With good detector resolution, hydrogen yield can be extracted. ● With very good res., event-by-event selection of ν-H interaction is possible.
Phys.Rev. D92 (2015) no.5, 051302
94
● Aim at first neutrino-pure hydrogen cross section measurement since 1986✔ Signal shape well known from detector simulation. ✔ Background can be further constrained by single-transverse kinematic imbalances
and measurements w/ pure nuclear target, e.g. graphite.● Precise probe of nuclear effects in pion production via H/C cross section ratio: detector
systemic uncertainties largely canceled (as C, H in same molecule).
Work in progress, Progress reports: arXiv:1605.00154, 1610.06244
T2K measurement of double-transverse kinematic imbalances
95
arXiv:1512.09042
2× better tracking res.
✔ Requirement on nuclear physics decreases as resolution improves! Only need to look at |δp
TT|<O(10 MeV) region.
T2K performance projection
96
Ideal acceptance w/ ideal tracking+PID
3-particle final state: µ, p, π+
Eν reconstructed as sum of final-state energy
H excl. pπ+ signal ➢ Fraction: ~ 20% (blue-shifted peak) – 10% (tail)
Recipe for nuclear-free neutrino energy spectra
97
Ideal acceptance w/ ideal tracking+PID
3-particle final state: µ, p, π+
Eν reconstructed as sum of final-state energy
H excl. pπ+ signal ➢ Fraction: ~ 20% (blue-shifted peak) – 10% (tail)➢ No (nuclear) bias in reconstructed E
ν
Recipe for nuclear-free neutrino energy spectra
98
Ideal acceptance w/ ideal tracking+PID
3-particle final state: µ, p, π+
Eν reconstructed as sum of final-state energy
H excl. pπ+ signal ➢ Fraction: ~ 20% (blue-shifted peak) – 10% (tail)➢ No (nuclear) bias in reconstructed E
ν➢ Can be extracted (statistically in realistic case)
Recipe for nuclear-free neutrino energy spectra
99
Ideal acceptance w/ ideal tracking+PID
3-particle final state: µ, p, π+
Eν reconstructed as sum of final-state energy
H excl. pπ+ signal ➢ Fraction: ~ 20% (blue-shifted peak) – 10% (tail)➢ No (nuclear) bias in reconstructed E
ν➢ Can be extracted (statistically in realistic case)➢ σ only nucleon cross section, Φ=N/(σ ∆Ε
ν)
➔ both Φ and Eν nuclear-free
➔ require tracking, PID (only needed for Εν
calculation), νH excl. pπ+ x-sec
Recipe for nuclear-free neutrino energy spectra
100
Ideal acceptance w/ ideal tracking+PID
3-particle final state: µ, p, π+
Eν reconstructed as sum of final-state energy
H excl. pπ+ signal ➢ Fraction: ~ 20% (blue-shifted peak) – 10% (tail)➢ No (nuclear) bias in reconstructed E
ν➢ Can be extracted (statistically in realistic case)➢ σ only nucleon cross section, Φ=N/(σ ∆Ε
ν)
➔ both Φ and Eν nuclear-free
➔ require tracking, PID (only needed for Εν
calculation), νH excl. pπ+ x-sec
Recipe for nuclear-free neutrino energy spectra
Same procedure for differential cross s
ections on W, Q
2 , etc.
101
Ideal acceptance w/ ideal tracking+PID
3-particle final state: µ, p, π+
Eν reconstructed as sum of final-state energy
H excl. pπ+ signal ➢ Fraction: ~ 20% (blue-shifted peak) – 10% (tail)➢ No (nuclear) bias in reconstructed E
ν➢ Can be extracted (statistically in realistic case)➢ σ only nucleon cross section, Φ=N/(σ ∆Ε
ν)
➔ both Φ and Eν nuclear-free
➔ require tracking, PID (only needed for Εν
calculation), νH excl. pπ+ x-sec
Recipe for nuclear-free neutrino energy spectra
Clean room for different exclusiv
e µpπ processes!
102
Outline
1. Understanding matter-antimatter asymmetry with neutrinos
2. Nuclear effects in neutrino-nucleus interactions
3. Measuring neutrino interactions
4. A neutrino shadow play
Act One: Neutrino energy independent measurement of nuclear effects
Act Two: Nuclear effect independent measurement of neutrino energy spectra
5. Summary
103
Summary (1)● NEW since 2016 summer:
– Doubled neutrino-mode statistics
– New reconstruction and event selection at SK: effective improvement in statistics by ~30%
– Improvements to neutrino interaction model
● Updated oscillation parameter estimates
– CP conserving values of δCP
are disfavored at 2σ level.
● T2K upgrade to collect 20×1021 POT and achieve 3σ (in case of favorable true values of δ
CP ) sensitivity to
exclude CP conserving values.
104
Summary (2)● It is important to understand nuclear properties in neutrino
interactions
– Future experiment requires total systematic errors better than few %.
● New technique to study nuclear and nucleon properties– Transverse kinematic imbalances
● correlation between final-state lepton and hadrons● Principle of solar eclipse: in the transverse plane, lepton kinematics is
used to cancel out nucleon level hadron kinematics; the rest is nuclear effects
– Single transverse kinematic imbalances: separate initial- and final-state nuclear effects
– Double transverse kinematic imbalance: modern measurement of ν-nucleon fundamental interaction
106
BACKUP
107
Impact of data-driven variation on sensitivity:
Will be addressed in future by 4π sample, hadronic recoil, ND upgrade
variation = pre-fit/model prediction difference at ND280
108
Quasi-elastic scattering (QE):
ω: energy transfer
109
Resonance production (RES):
ω: energy transfer
110
Deep inelastic scattering (DIS): nucleon breaks up
ω: energy transfer
111
ω: energy transfer
For QE and RES (nucleon not breaking up), ω “saturates” when E
ν > 0.5 GeV
[Phys.Rev. C94 (2016) no.1, 015503]
112
In QE and RES ● Lepton retains most of the increase of E
ν
● Leptonic kinematics much more Eν-dependent than
hadronic ones
Source: http://www.wikihow.com/Pump-a-Spalding-Neverflat-Basketball
ν
N
l'
For QE and RES (nucleon not breaking up), ω “saturates” when E
ν > 0.5 GeV
[Phys.Rev. C94 (2016) no.1, 015503]
ω: energy transfer
113
END
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