1. 一般化されたパートン分布関数：実験の現状
Sept 27, 2004 at Kochi, JPS
一般化されたパートン分布関数：実験の現状
東工大　柴田利明　
T.-A. Shibata

2. 1. 陽子のスピン構造、一般化されたパートン分布関数 2. 実験の現状、 Exclusive Process (排他的過程）
一般化されたパートン分布関数：　実験の現状 目次
1.　陽子のスピン構造、一般化されたパートン分布関数
2.　実験の現状、　Exclusive Process　(排他的過程）
3.　電子散乱－Deeply Virtual Compton Scattering
　　　　　　　　　 （深仮想コンプトン散乱）
4.　ニュートリノ散乱
5.　展望とまとめ
T.-A. Shibata

3. Introduction : Spin of Proton
1 / 2
SU(6) Quark Wave Functions of Baryons
1 / 2
Sum of Spins of u u d Quarks = Spin of Proton + + =
1 / 2
- 1 / 2
EMC Experiment (1988)
20 – 30 % of Nucleon Spin
T.-A. Shibata
‘Nucleon Spin Problem’

4. EMC + Neutron lifetime Hyperon weak decays 1/2 sum
0.2
0.4
-0.2
-0.4
sum
1/2
flavor SU(3) symmetry
assumed
T.-A. Shibata

5. Experiments on the Proton Spin and related measurements
Fixed Target Experiments:
CERN EMC, SMC, COMPASS GeV pol p,d DIS
DESY-HERA HERMES e 28 GeV pol p,d DIS
SLAC e 50 GeV pol 3He, p,d DIS
JLAb Hall A e 6 GeV pol 3He DIS
Hall B e 6 GeV pol p,d Resonance Reg.
Hall C e 6 GeV pol p,d Resonance Reg.
MIT/Bates SAMPLE e 0.2 GeV p,d Elastic Scatt. PV
JLAB G e 6 GeV p,d Elastic Scatt. PV
JLAB HAPPEX e 6 GeV p,d Elastic Scatt. PV
Mainz-MAMI e 0.88 GeV p,d Elastic Scatt. PV
BNL　　　　　E734　　　　　　　　　　　　　　 　1.3 GeV p Elastic Scatt. NC
　Collider Experiments:
BNL-RHIC PHENIX p+p 200 or 500 GeV gluon spin, sea quark
STAR p+p 200 or 500 GeV gluon spin, sea quark
KEK B-factory BELLE e + e, 8 on 3.5 GeV fragmentation function
T.-A. Shibata

6. Deep Inelastic Scattering, Semi-inclusive Measurements
Inclusive measurement, e’ e’
Semi-inclusive measurement,
e’ and e
Flavor tagging
Factorization:
( quark distribution ) x
( fragmentation function )
T.-A. Shibata

7. Theory: for example, OFF FORWARD PARTON DISTRIBUTIONS X. D. Ji,
J. Phys. G24 (1998)
DEEPLY VIRTUAL COMPTON SCATTERING
Phys. Rev. D55 (1997)
…..
T.-A. Shibata

8. Deeply Virtual Compton Scattering
Generalized (Off-Forward) Parton Distributions
Deeply Virtual Compton Scattering
Exclusive Meson Production
Deep Inelastic
Scattering
Generalized Parton Distributions (GPD)
Electromagnetic Form Factors
( Elastic Scattering )
Total Angular Momentum Jq
Orbital Angular Momentum Lq
T.-A. Shibata

9. Sum rules, x – integral, sum over q
Generalized (Off - Forward) Parton Distributions
Forward limit
Ordinary Quark
Distributions
Sum rules, x – integral, sum over q
Dirac and Pauli Nucleon
Form Factors
Axial-vector and Pseudo-
scalar Form Factors
2nd moment
Total angular momentum
Orbital angular momentum
T.-A. Shibata

10. Experimental Methods and Results
T.-A. Shibata

11. Double-spin asymmetry Polarized e, 1994
Quark Helicity Distributions, Flavor Separation
Double-spin asymmetry
Polarized e, 1994
Beam and target, both polarized
Virtual photon
Nucleon
T.-A. Shibata

12. HERMES (2004), hep-ex/ A1
positive
negative ｘ
T.-A. Shibata

13. x x HERMES Flavor Separation, Quark Helicity Distributions Result:
X bin by bin analysis except
for smearing correction.
No functional forms are
assumed.
No first moments are assumed.
Helicity conservation not
assumed
Error band – systematic error x
QCD fits to inclusive
measurements
T.-A. Shibata x

14. Deeply Virtual Compton Scattering
「HERMESによるHard Exclusive 生成過程の測定：一般化されたパートン分布関数による核子構造の研究」
宮地義之、柴田利明、高エネルギーニュース, 22 (2003) 11
T.-A. Shibata

15. Inclusive Measurement:
Total cross section for virtual photon – nucleon reaction
T.-A. Shibata

16. Im Deeply Virtual Compton Scattering Coss section for (DVCS)
-- Exclusive production of a real photon
Coss section for
inclusive deep inelastic
scattering Im
GPD
:Light cone momentum fraction
:Exchanged longitudinal momentum fraction
:Momentum transfer
T.-A. Shibata

17. How to measure DVCS Deeply Virtual Compton Scattering
Bethe-Heitler Process, known
calculable
Beam-spin asymmetry by HERMES and CLAS
Beam-charge asymmetry by HERMES
-- DVCS-BH Interference, Real and Imaginary
T.-A. Shibata
DVCS Cross Section by ZEUS and H1

18. Deeply Virtual Compton Scattering
First observation of beam-spin asymmetry of DVCS
HERMES (DESY)
CLAS (JLab)
~ 30% effect
T.-A. Shibata

19. Beam-Spin Asymmetry HERMES Missing Mass Resolution 0.8 GeV
Deeply Virtual Compton Scattering, Generalized Parton Distributions
Beam-Spin Asymmetry
HERMES
T.-A. Shibata
Missing Mass Resolution 0.8 GeV

20. How to extend Quantum number of final state Select different GPD
Exclusive Meson Productions
GPD
GPD
Pseudo scalar meson
Vector meson
HERMES’s data
T.-A. Shibata

21. Neutrino beam experiments
T.-A. Shibata

22. neutrino-proton elastic form factor and
How to measure:
T.-A. Shibata

23. FINNeSSE at FNAL and BNL, Experiment at J-PARC (NP04, Aug. 2004)
Neutrino-nucleon elastic scattering cross section
from viewpoint of strange quark spin in the proton
E734
L.A. Ahrens et al., Phys. Rev. D35 (1987) 785,
G.T. Garvey et al., Phys. Rev. C48 (1993) 761
BNL734 experiment with
Neutrino beam from AGS on proton,
(mean energy 1.3 GeV) , (1.2 GeV)
FINNeSSE at FNAL and BNL,
Experiment at J-PARC (NP04, Aug. 2004)
T.-A. Shibata

24. Neutrino Flux at J-PARC, 50 GeV proton, at 280 m
T.-A. Shibata

25. Parton Distribution q(x), Form Factors, and excluive
Summary and Outlook
Page 1
Many experiments on Spin Structure of the Proton are going on and are planned all over the world.
Genaralized (Off-Forward) Parton Distribution is a ‘Grand Unified Theory’ of Hadrons
Parton Distribution q(x), Form Factors, and excluive
processes can be analysed in the same framework.
Deeply Virtual Compton Scattering, in particular its spin dependence, has been measured.
T.-A. Shibata

26. Form Factors from Neutrino Scattering are important elements.
Page 2
Form Factors from Neutrino Scattering are important elements.
Exclusive Process of Hadron Reactions (gluon Compton scattering, 2 jet productions in pp collisions) will also contribute.
= 200 GeV, Lint = 320 pb-1, beam polarization 70% for
gluon Compton scattering,
= 500 GeV, Lint = 800 pb-1, beam polarization 70% for W production,
With this universal theoretical framework, the studies of spin structure of the proton will be further developed.
Collaborative studies in Japan will be important.
T.-A. Shibata

27. RHIC－SPIN Experiments:
Polarized Proton-Proton Collision
= 500 GeV, Lint = 800 pb-1, beam polarization 70%
using known
T.-A. Shibata

28. = 200 GeV, Lint = 320 pb-1, beam polarization 70%
direct photon productions
2 jet production
Gluon Compton scattering
Inclusive
T.-A. Shibata