KEK研究会「核子の構造関数２００８」

２００８年１月１２日＠ＫＥＫ

ニュートリノ散乱によるΔｓ測定
Yoshiyuki Miyachi, Tokyo Tech

• Proton Spin Problem and Δs– SU(3) flavor symmetry– Nucleon Form Factors• Neutrino Scattering and Δs– E734, SciBooNE (FINeSSE)– Model calculation– Experiment at J-PARC• SummaryProton spin problem and Δs- EMC results -Nucl. Phys. B328 (1989) 1, Phys. Lett. B206 (1988) 364

Polarized DIS:  ' X
 N
Structure Function

F i  x ,Q 2  , g i  x ,Q 2 µParton Distributionq  x , Q 2 ,  q x ,Q 2 111
∫0 dx g  x = 9 a0 12 a3 36 a8
X=0.126±0.01±0.015
SU(3) flavor symmetry
1

P= M ,0p1

a 3=1.26 , a 8=0.58

a 0= u d  s=0.1201/12@KEK「核子の構造関数２００８」

 s=−0.19
Yoshiyuki Miyachi, Tokyo Tech

Updated results on g1 and Δs
Phys. Rev. D 75 (2007) 012007
0.9∫0.021 g 1  x ,5 GeV dx=
d2

0.0436±0.0012±0.018±0.0008±0.0026

Assumption:" High x contribution = 0" Saturation in the lower x region" SU(3) flavor symmetry:2 s 5 GeV =−0.085±0.013±0.008±0.009

Assuming SU(3) flavor symmetry
Phys. Lett. B 647 (2007) 8:

01/12@KEK s ∞=−0.08±0.01±0.02「核子の構造関数２００８」

Yoshiyuki Miyachi, Tokyo Tech

Flavor tagging in DIS
l  N  l ' h X
Structure Function
22F i  x ,Q  , g i  x , Q d 3  h22h2∝eqx,QDz,Q∑
q2i qdx dz dQz=Parton Distribution
2P⋅ph E h=P⋅q

2qx ,Q , qx ,Q 

Flavor Tagging:
Hadron carries information onquark flavor

P= M ,0hq

2Fragmentation D  z , Q through fragmentation function

p h= E h , p h 01/12@KEK「核子の構造関数２００８」

Yoshiyuki Miyachi, Tokyo TechStrangeness spin inside proton  e' hX
e  N s  x =0- HERMES results -assumed

Phys. Rev D 71 (2005) 012003

assumingΔq(x)=00.6

 q=∫0.023 dx  q x 2Q =2.5 GeV2

 u=0.601±0.039±0.049
 d =−.226±0.039±0.050
 u =−.002±0.036±0.023
 d =−.054±0.033±0.011
 s=0.028±0.033±0.009
01/12@KEK- without SU(3) symmetry assumption- only partial moments are available- “LO” extraction「核子の構造関数２００８」

Yoshiyuki Miyachi, Tokyo Tech

SU(3) violation and impact on ∆s
J. Lichtenstadt and H. J. Lipkin, Phys. Lett. B353 (1995) 119

E. Leader et. al., Phys. Lett. B488 (2000) 283

SU(3): symmetry↔

violation

χQM calculation:(X. Song et. al, Phys. Rev. D55 (1997) 2624-2629)
SU(3) symmetry:∆s = -0.1
SU(3) breaking:∆s = -0.05
01/12@KEK「核子の構造関数２００８」

Yoshiyuki Miyachi, Tokyo TechNeutrino-Nucleon scattering
2F2GdQ2
A±BW ±CW =22dQ 2  EA =B =C =[4 E Q 2W=− 2m p mp

1 2G1 1 −F 12− F 221− 4 F 1 F 241− G 1 F 1 F 2 421 mp 222GFF
11216 Q2]

2Q
=4m 2p

NC-EL/CC-QE

Neutral Current[[[F 1,2 =]11 spn2pn−sin 2 W [F 1,2−F 1,2−sinFF−F 1,2]
W [ 1,21.2 ]22sGAGA
G 1= −  z2201/12@KEK]sA]
2G Q =0= s「核子の構造関数２００８」

Yoshiyuki Miyachi, Tokyo TechNeutrino scattering and s- E734 results -• Neutral current elastic scattering cross section• Liquid scintillator + Drift Tube 170 t• 0.5E19 POT for neutrino• 2.5E19 POT for anti-neutrino

E734, Phys. Rev. D35 (1987) 785• From GAs(Q2) to ss
2– G A Q 0= s=−0.21±0.10• Further analysis based on E734
RNC /CC =0.152±0.007±0.017
RNC /CC =0.218±0.012±0.023
RNC/ =0.302±0.019±0.037 0.5Q 21.0 GeV2-0.21 < s < 001/12@KEK

strong correlation with the axial mass MA
Q2 dependence of GsA「核子の構造関数２００８」

Yoshiyuki Miyachi, Tokyo TechFINeSSE @ FNALFINeSSE Proposal, hep-ex/0402007

FNAL booster neutrino beam-line

01/12@KEK「核子の構造関数２００８」

νμ 6E20 POT

Yoshiyuki Miyachi, Tokyo TechFINeSSE SciBath detector

FINeSSE Proposal, hep-ex/0402007

Liquid Scintillator
MC NC elastic event p   p

WLS readout- Target: C in SciBath- R(NC/CC) measurement
cancellation of flux and nuclear effectδ(Δs) = 0.04 (sta. + sys.), (+ 0.025 from form factors)
01/12@KEK「核子の構造関数２００８」

Yoshiyuki Miyachi, Tokyo TechMiniBooNE

ν

SciBooNE@FNAL

Production target

01/12@KEK「核子の構造関数２００８」

Yoshiyuki Miyachi, Tokyo TechNeutrino scattering cross section (CC)01/12@KEK「核子の構造関数２００８」

Yoshiyuki Miyachi, Tokyo TechSciBooNE @ FNAL

" SciBar/EC detector from K2K" Muon Range Detector
Primary physics goal:
precise cross section measurements ofnon-QE ν-interaction, anti-ν interaction

01/12@KEK「核子の構造関数２００８」

Yoshiyuki Miyachi, Tokyo Tech

(NuFact06, H. Tanaka)

01/12@KEK「核子の構造関数２００８」

Yoshiyuki Miyachi, Tokyo TechSciBar Event Display with K2K data

NC candidate
NC-π0 candidate p  p

NR NC /CC= n   pN
Neutron background should be
carefully studies.
01/12@KEK「核子の構造関数２００８」

CC-QE candidate
Yoshiyuki Miyachi, Tokyo TechExpected yields
With 1E20 POT neutrino
1/3 of FINeSSE (59K)
FINeSSE: δ(Δs)~0.04
SciBooNE: δ(Δs) ?
With 1E20 anti-neutrino
NCE ~ 3k

SciBooNE prolongation- One page “proposal” was submitted to FNAL on Δs measurement as extension of SciBooNE
01/12@KEKhttp://www.fnal.gov/directorate/Longrange/Steering_Public/community_letters.html「核子の構造関数２００８」 Yoshiyuki Miyachi, Tokyo TechSciBooNE: status and plan
- SciBar and EC were moved from
SciBooNE Event Display:
KEK to FNAL (Jul. 2006)
with anti-neutrino beam
- Civil construction started (Sep.
2006)- Commissioning done (Apr. 2007)- Physics RUN : ( May ~ Aug. 2007)
with anti-neutrino mode
5E19 POT delivered- Detector live time: 96.5%
beam- Calibration of the detectors ison going.
- Physics RUN with neutrino mode
(Oct. 2007 ~ ) 4.3E19 POT delivered
neutrino CC-QE candidate- Switch back to anti-neutrino mode(Spring 2008)- R(NC/CC) study is on going.
01/12@KEK「核子の構造関数２００８」Yoshiyuki Miyachi, Tokyo TechAccumulated POT by SciBooNE

01/12@KEK「核子の構造関数２００８」

Yoshiyuki Miyachi, Tokyo TechSciBar Performance

Time distribution
Event rate per week

01/12@KEK「核子の構造関数２００８」

Yoshiyuki Miyachi, Tokyo Tech

Nuclear effects
on extraction of strange quark component
PHYSICAL REVIEW C 76, 055501 (2007)
Strangeness content of the nucleon in quasielastic neutrino-nucleus reactions
N. Jachowicz, P. Vancraeyveld, P. Lava, C. Praet, and J. Ryckebusch

01/12@KEK「核子の構造関数２００８」

Yoshiyuki Miyachi, Tokyo TechPHYSICAL REVIEW C 76, 055501 (2007)

Nuclear target: A relativistic mean-field approach
FSI: A relativistic multiple-scattering Glauber approachC C

01/12@KEK「核子の構造関数２００８」

Yoshiyuki Miyachi, Tokyo Tech

Comparison with other models...

PHYSICAL REVIEW C 76, 055501 (2007)

01/12@KEK「核子の構造関数２００８」

Yoshiyuki Miyachi, Tokyo Tech

Nuclear EffectQ2 dependenceΔsNormalization
flux/background

Strange form
factors

Accurate measurement of NC ν-H in 0.1 < Q2 < 0.4 GeV2
which is covered by the electron scattering.
01/12@KEK「核子の構造関数２００８」

Yoshiyuki Miyachi, Tokyo Tech

J-PARC ν-beam line
• Beam flux
– 1 GeV for “on-axis”– < 1GeV for “off-axis”• 1021 POT/year (130 days)• anti-neutrino beam
– neutrino anti-neutrino
asymmetry measurement

Expected ν flux (MC data)

01/12@KEK「核子の構造関数２００８」

Yoshiyuki Miyachi, Tokyo Tech

Methods of ∆s measurement• Nuclear effect (ex. C target):– Nuclear model uncertainty on ∆s extraction• R(NC/CC) measurements:– Neutrino flux should be canceled. It also suppresses thenuclear effect.
– Is there any model dependence uncertainty?

• ν-H scattering extraction:– Using two targets with different mixture of H and C• Separation of ν-H and ν-C scattering becomes possible– Neutrino flux information is needed to extract the crosssection.
01/12@KEK「核子の構造関数２００８」

Yoshiyuki Miyachi, Tokyo TechExtraction of NNCH
Nuclear effect free extraction:
Using two liquid scintillators with different mixture of H and C:

BICRON: H/C
BC501A 1.212
BC533
1.96
HNCCNCρ(g/cm3)
0.874
0.8BC533
NCBC533
NC

N =23.4×N
N =−2.36×N

ρH(g/cm3) ρC(g/cm3)
0.112
0.688
0.080
0.794
BC501A
NCBC501A
NC−20.3×N
3.30×N( ~ 15% *NNC )(FINeSSE: δ(Δs)~0.04 with 6E20 POT + 9 t)
01/12@KEK「核子の構造関数２００８」

Yoshiyuki Miyachi, Tokyo TechDual SciBath configuration

5m5BC501A

BC533

WLS readout

m5m
Fiducial volume:
3x3x3 m3

Geant4 data
ν: 500 MeV
p: 270 MeV

01/12@KEK「核子の構造関数２００８」

Yoshiyuki Miyachi, Tokyo TechExpected sensitivity
1E21 POT (off-axis)+ 2 * 27 t SciBath
Stat. + Sys. errors

Statistical error onlyδ(Δs) = 0.03
(dipole form factor)

Expected sensitivity assuming the dipole approximation:

δ(Δs) = 0.03
Systematic errors must be studied carefully. (Normalization, Background)
01/12@KEK「核子の構造関数２００８」

Yoshiyuki Miyachi, Tokyo TechSummary• Proton spin problem– Δs is a key for understanding of sea quark contribution• HERMES, COMPASS: Δs = -0.08 ± 0.02 with SU(3) symmetry• HERMES SIDIS: Δs = 0.03 ± 0.03 ( partial, no SU(3) symmetry)– Flavor SU(3) symmetry? breaking?
– Strange nucleon form factor can constrain directly Δs• Neutrino scattering: NC elastic scattering– E734 NC cross section measurements : -0.2 < Δs < 0.0– FINeSSE proposed R(NC/CC) measurement : δ(Δs) = 0.04

– SciBooNE: Data taking was started in 2007
• Smooth data taking. 1E20 POT for both neutrino and anti-neutrino• R(NC/CC) study is on going. Feasibility study on Δs extraction
01/12@KEK「核子の構造関数２００８」

Yoshiyuki Miyachi, Tokyo TechSummary• Prolongation of SciBooNE– http://www.fnal.gov/directorate/Longrange/Steering_Public/community_letters.html• Δs measurement at J-PARC– Measurement of NC cross section on H, not R(NC/CC)– Sensitivity study based on• 1E21POT neutrino beam at 280m away from the production target• Dual SciBath detector• δ(Δs) ~ 0.03 expected (with dipole form factor assumption)• Normalization and background contributions to the systematic error tobe studied.
• Q2 extrapolation (Q2 dependence) also has to be carefully studied.

01/12@KEK「核子の構造関数２００８」

Yoshiyuki Miyachi, Tokyo Tech

END
01/12@KEK「核子の構造関数２００８」

Yoshiyuki Miyachi, Tokyo Tech