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Higher Fock State Contributions to Generalized Parton Distributions

Higher Fock State Contributions to Generalized Parton Distributions. Beijing, June 14, 2006. Workshop on Future PRC-U.S. Cooperation in High Energy Physics. Motivation for Two-Photon Physics. - GPDs Contain Much More Information than DIS and FF.

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Higher Fock State Contributions to Generalized Parton Distributions

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  1. Higher Fock State Contributions to Generalized Parton Distributions Beijing, June 14, 2006 Workshop on Future PRC-U.S. Cooperation in High Energy Physics

  2. Motivation for Two-Photon Physics - GPDs Contain Much More Information than DIS and FF. Quark distribution q(x) DIS only measures a cut at =0 Antiquark distribution q(x) qq distribution DVCS SSA Measurements (JLAB/CLAS,DESY/HERMES) - LFQM has also progressed for last several years.

  3. Outline • DVCS SSA Expt’l Results - DESY/HERMES PRL87,182001 (2001) - JLAB/CLAS PRL87,182002 (2001) • GPD at Crossover Point • Continuity Issue H.-M.Choi,C.Ji,L.S.Kisslinger,PRD66,053011(2002) • Nonzero Value C.Ji,Y.Mishchenko,A.Radyushkin,PRD in press;hep-ph/0603198 • PQCD Connection • Real and Virtual Compton Scattering R.Thomson, A.Pang and C.Ji, PRD73, 054023(2006) • Conclusions

  4. Beam-Spin Asymmetry Measurements HERMES Collab E=27.6 GeV PRL87,182001(2001) CLAS Collab E=4.25 GeV PRL87,182002(2001)

  5. Crossover point Interference between DVCS and BH

  6. GPDs provide access to fundamental quantities such as the quark orbital angular momentum that have not been accessible • and the GPDs unify the description of inclusive and exclusive processes, connecting directly to the “normal” parton distributions: Generalized Parton Distributions

  7. ~ ~ H , E , H , E ~ H0(x,0) = Dq(x) polarized = D 2 t Ordinary Parton Distributions (D, t, x→ 0) Limiting Cases for GPDs H0(x,0) = q(x) unpolarized Nucleon Form Factors (Sum Rules) x P (x-x) P Dirac Axial vector P PD Pauli Pseudoscalar

  8. GPD Application: DVCS C.Ji, Y.Mishchenko, A.Radyushkin, PRD in press; hep-ph/0603198 H.-M.Choi, C.Ji, L.Kisslinger, PRD66, 053011 (2002)

  9. GPD Application: DVCS (cont’d)

  10. Embedded State: Non-wavefunction Vertex C.Ji & H.-M.Choi, PLB513, 330 (2001) B.Bakker & C.Ji, PRD62, 074015 (2000)

  11. Semi-leptonic Decay C.Ji & H.-M.Choi, PLB513, 330 (2001)

  12. GPD Results H.-M.Choi,C,Ji and L.S.Kisslinger, Phys.Rev.D66,053011(2002)

  13. Higher Fock State Contributions to GPD

  14. Higher Fock State Contributions to GPD C.Ji,Y. Mishchenko,A.Radyushkin,PRD in press; hep-ph/0603198

  15.  GPD at =0.1, 0.3, 0.5, 0.7

  16. LFD in Exclusive Processes q+ + + Absent in q+ = 0 Absent

  17. x1 y1 x2 y2 |q2| >> LQCD 2 x3 y3 TH f f LFD in Exclusive Processes q+ + + Absent in q+ = 0 Absent

  18. The Quark Counting Rule and PQCD Predictions of Exclusive Processes 6x7x8=336 Pang & Ji, J.Comp.Phys.115,267(94) R. Thomson, A. Pang and C.Ji, PRD73,054023(2006)

  19. Comparison with previous work for real photon T. Brooks and L. Dixon, PRD62, 114021 (2000) M. Vanderhaeghen, P.Guichon and J. Van de Wiele, NPA622, 144 (1997) A. S. Kronfeld and B. Nizic, PRD44, 3445 (1991) G. R. Farrar and H. Zhang, PRD41, 3348 (1990);42, 2413(E) (1990)

  20. Virtual photon, COZ: incoming photon up and down

  21. Virtual photon, COZ: incoming photon longitudinal

  22. Checking Handbag Dominance in PQCD Work in progress …

  23. Conclusions • Two-photon physics provides much more abundant informations on the hadron structure than single-photon physics. • GPD at the crossover point does not necessarily vanish in LFQM. • Higher Fock state contributions provide nonzero values of GPD at crossover points and a clue to understand the measured beam-spin asymmetries at JLAB/CLAS and DESY/HERMES. • With the progress of symbolic software packages, PQCD can also provide a link to the GPD analyses checking the dominance of handbag approach in DVCS.

  24. Effective LFQM for Low Q2 Radial Spin-Orbit (Dependent on the model potential) (Interaction independent Melosh transformation) H = T + V V includes Coulomb, Confinement, Spin-Spin,Spin-Orbit interactions.

  25. New Meson Spectroscopy 2.00 2.00 2.0 1.89 1.82 1.88 1.82 1.82 1.82 1.78 1.78 1.78 1.78 1.5 1.46 1.45 1.31 1.31 1.30 1.24 1.24 1.29 1.22 1.22 1.09 1.09 1.0 0.77 0.77 0.5 0.15 0.15 1S0 (0-+) 3S1 (1--) 1P1 (1+-) 3P0 (0++) 3P2 (2++) 3P1 (1++) Godfrey and Isgur DeWitt and Ji

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