Extraction of parton distributions and $\alpha_s$ from DIS data within the Bayesian treatment of systematic errors

Abstract

We have performed the NLO QCD global fit of BCDMS, NMC, H1 and ZEUS data with full account of point-to-point correlations using the Bayesian approach to the treatment of systematic errors. Parton distributions in the proton associated with experimental uncertainties, including both statistical and systematic ones were obtained. The gluon distribution in the wide region of $x$ was determined and it turned out to be softer than in the global analysis using prompt photon data. We also obtained the robust estimate of $\alpha_s(M_Z) = 0.1146\pm0.0036 (75% C.L.)$ based on Chebyshev's inequality, which is compatible with the earlier determination of $\alpha_s$ from DIS data, but with less dependence on high twist effects.