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Paper   IPM / Physic / 7635
School of Physics
  Title:   Next-to-Leading Order Approximation of Polarized Valon and Parton Distributions
1.  Ali N. Khorramian
2.  A. Mirjalili
3.  S. Atashbar Tehrani
  Status:   Published
  Journal: JHEP
  Vol.:  10
  Year:  2004
  Pages:   062
  Supported by:  IPM
Polarized parton distributions and structure functions of the nucleon are analyzed in the improved valon model. The valon representation provides a basis between hadrons and quarks, in terms of which the bound-state and scattering properties of hadrons can be united and described. Polarized valon distributions are defined to have an important role in describing the spin dependence of parton distribution in leading order and next-to-leading order approximation. In polarized case, convolution integral is derived in frame work of valon model. Polarized valon distribution in a proton and polarized parton distributions inside the valon are necessary to obtain polarized parton distributions in a proton. Bernstein polynomial averages are used to get unknown parameters of polarized valon distributions by fitting to available experimental data. The predictions for NLO calculations of polarized parton distributions and proton structure function have been compared with LO approximation . It is shown that the results of the calculations for proton structure function, xg1p , and the first moment of proton, Γ1p, are in good agreement with experimental data for some value of Q2. Finally the spin contribution of valons and proton are calculated.

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