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We perform N3LO QCD analysis of the world data on the unpolarized DIS structure functions to determine s and valance quark distributions with fully correlated errors. Due to increasing the accuracy of DIS experiments and reduction the experimental errors on determining the strong
coupling constant, the higher order analysis is required. The Padï¿½ approximations are used to estimate the 4-loop anomalous dimension. We consider the non-singlet sector of parton distributions in our calculations. A comparison of the N3LO/N2LO with N3LO/NLO ratios for up and down
valence quark distributions indicate outstanding influence of the higher order analysis.
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