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Accessing Orbital Angular Momentum Thru Pion Cloud Itaru Nakagawa RIKEN/RBRC.

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Presentation on theme: "Accessing Orbital Angular Momentum Thru Pion Cloud Itaru Nakagawa RIKEN/RBRC."— Presentation transcript:

1 Accessing Orbital Angular Momentum Thru Pion Cloud Itaru Nakagawa RIKEN/RBRC

2 Proton Spin +1/2

3

4 P-wave

5 Proton Spin +1/2

6

7

8 P-wave

9 Nucleon EM Form Factors

10 Nucleon EM Form Factors low Q

11 Nucleon EM Form Factors phenomenological fit : “smooth” part (sum of 2 dipoles) + “bump” (gaussian) 6 parameter fit for each FF pronounced structure in all FF around Q  0.5 GeV/c pion cloud J.Friedrich & Th. Walcher, EPJA A17, 607 (2003)

12 Sea Asymmetry from Drell-Yan Processes Towell et al., Phys.Rev. D64 (2001) 052002 Profounding Example of Pion Cloud

13 excess Extra dbar in proton g.s. Sea Quarks Carry Major Orbital Angular Momentum Component?

14 Pion Model Prediction of Orbital Angular Momentum A.W. Thomas JLab

15 Tony Thomas (3)

16 Tony Thomas (1)

17 Proton Spin +1/2 70%20~25%5~10%

18 Tony Thomas (2)

19 Tony Thomas (4)

20 Tony Thomas

21 Tony Thomas(6)

22 Experiment Sensitive to p-Wave 

23 Angular Distribution

24 Pion Cloud Model

25 Atomic Electron Scattering Virtual pion pickup Probing Pion Cloud Need : Q 2 ~ 0.2 GeV/c 2  Compass Calculation by T. Horn +

26 Summary pion cloud is one of the way to access Orbital Angular Momentum There are (will be) many experiments which explore pion cloud Not good idea yet to be done at J-PARC

27 Elastic Scattering

28 Cross Sections

29 Valence Quark Interchange

30 Concerns So far, q-interchange model is only quantitative level  Qualitatively, regge pole) Elastic  Soft Mechanism Elastic  No Fragmentation? Sensitivity to sea? p

31 Relativistic Valence Quark rXiv:0709.4067 ハ [hep-ph]


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