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Ali. N. Khorramian (IPM), Institute for studies in theoretical Physics and

Ali. N. Khorramian (IPM), Institute for studies in theoretical Physics and Mathematics Physics Department, Semnan University. Workshop on Low-x physics 16-19 September 2002. Polarized Structure Function.

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Ali. N. Khorramian (IPM), Institute for studies in theoretical Physics and

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  1. Ali. N. Khorramian (IPM), Institute for studies in theoretical Physics and Mathematics Physics Department, Semnan University Workshop on Low-x physics 16-19 September 2002

  2. Polarized Structure Function Workshop on Low-x physics 16-19 September 2002

  3. Ali. N. Khorramian (IPM), Institute for studies in theoretical Physics and MathematicsPhysics Department, Semnan Universitykhorramiana@theory.ipm.ac.irS. Atashbar TehraniPhysics Department, Persian Gulf Universityatashbar@cic.aut.ac.ir Workshop on Low-x physics 16-19 September 2002

  4. Outline   I. Valon model        II. Unpolarized and polarized valon distribution         III. Polarized parton distributions       IV. Proton and Neutron polarized structure functions.   V. Summary & Outlook

  5. Some experimental data for p, n, d E80, 130 (p) ; E142 (n) E143 (p, d) ; E154 (n) ; E155 (p, d) EMC, SMC (p, d) HERMES (p, d, n) Workshop on Low-x physics 16-19 September 2002

  6. F. Arash and Ali N. Khorramian Nucl. Phys. B 99, 164 (2001) Workshop on Low-x physics 16-19 September 2002

  7. Workshop on Low-x physics 16-19 September 2002

  8. What is the valon model?The valon model describes the hadron structure relevent for multiparticle production.The polarized valon is defined to be a dressed valence quark in QCD with the cloud of polarized gluons and sea quarks which can be resolved by high Q^2 probes. At sufficiently low value of Q^2 the internal polarized structure of a valon cannot be resolved and hence it behaves as a polarized valence quark. For example in the proton we have 2 U-valons and one D valon.   I. Valon model Workshop on Low-x physics 16-19 September 2002

  9. Unpolarized Valon distribution in a proton • To facilitate the phenomenological analysis Hwa assumed a simple form for the exclusive valon distribution in unpolarized proton which is Where yi is the momentum fraction of the i-th valon. • The single valon distributions are obtained by integration R. C. Hwa and C. B. Yang , hep-ph /0202140 Workshop on Low-x physics 16-19 September 2002

  10. Unpolarized valon U U D F. Arash and Ali N. Khorramian Nucl. Phys. B 99, 164 (2001) Ali N. Khorramian, F. Arash , Structure of Hadrons, Proceedings of the International Workshop XXIX on Gross Properties of Nuclei and Nuclear Excitations Hirschegg, Austria, (2001) R. C. Hwa and M. S. Zahir, Phys. Rev. D 23, 2539 (1981); … R. C. Hwa and C. B. Yang , hep-ph /0202140 Workshop on Low-x physics 16-19 September 2002

  11. Polarized Valon distribution in a proton Workshop on Low-x physics 16-19 September 2002

  12. Unpolarized and polarized valon distribution in a proton Workshop on Low-x physics 16-19 September 2002

  13. Workshop on Low-x physics 16-19 September 2002

  14. Polarized valon distribution in a proton Workshop on Low-x physics 16-19 September 2002

  15. For calculating the LO and NLO evolutions of the spin-dependent parton distributions, we have used the well known analytic LO and NLO solution in Mellin n-moment space with the n-th moment being defined by Workshop on Low-x physics 16-19 September 2002

  16. III. Workshop on Low-x physics 16-19 September 2002

  17. LO Workshop on Low-x physics 16-19 September 2002

  18. Workshop on Low-x physics 16-19 September 2002

  19. Moments of polarized parton distributions Workshop on Low-x physics 16-19 September 2002

  20. Polarized parton distributions as a function of x Workshop on Low-x physics 16-19 September 2002

  21. NLO Workshop on Low-x physics 16-19 September 2002

  22. Workshop on Low-x physics 16-19 September 2002

  23. Moments of polarized parton distributions in LO and NLO Workshop on Low-x physics 16-19 September 2002

  24. Workshop on Low-x physics 16-19 September 2002

  25. Workshop on Low-x physics 16-19 September 2002

  26.     IV. Proton and Neutron polarized structure functions. Workshop on Low-x physics 16-19 September 2002

  27. Workshop on Low-x physics 16-19 September 2002

  28. Polarized structure function in LO Workshop on Low-x physics 16-19 September 2002

  29. Polarized structure function in NLO Workshop on Low-x physics 16-19 September 2002

  30. The compare of our predictions for polarized proton structure function from our model with the measured structure functions in experiments on proton target. Workshop on Low-x physics 16-19 September 2002

  31. The compare of our predictions for polarized proton structure function from our model with the measured structure functions in experiments on proton target. Workshop on Low-x physics 16-19 September 2002

  32. Workshop on Low-x physics 16-19 September 2002

  33. Plots of neutron polarized structure function against x at Q^2= 2, 3 GeV^2 Workshop on Low-x physics 16-19 September 2002

  34. Plots of neutron polarized structure function against x at Q^2= 5 GeV^2 Workshop on Low-x physics 16-19 September 2002

  35. conclusion • We have presented a model that be used for extraction polarized parton distributions. • Our results for polarized proton and neutron structure functions are good agrement with available experimental data.

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