Symmetry breaking effect on determination of polarized and unpolarized   parton distributions
  We perform a new extraction for unpolarized and polarized parton distribution functions considering a flavor decompositions for sea quarks and applying very recent deep inelastic scattering (DIS) and semi inclusive deep inelastic scattering (SIDIS) data in the fixed flavor number scheme (FFNS) framework. In the new symmetry breaking scenario the light quark and antiquark densities are extracted separately and new parametrization forms are determined for them. The heavy flavors contribution, including charm and bottom quarks, are also taken to be account for unpolarized distributions. 
F. Arbabifar, Ali. N. Khorramian, H. Khanpour, S. Atashbar Tehrani
hep-ph