A systematic study of QCD coupling constant from deep-inelastic measurements

AbstractWe reanalyze deep-inelastic scattering data of the BCDMS Collaboration by including proper cuts of ranges with large systematic errors. We also perform the fits of high-statistic deep-inelastic scattering data of the BCDMS, SLAC, NM, and BFP Collaborations taking the data separately and in a combined way and find good agreement between these analyses. We extract the values of both the QCD coupling constant αs(MZ2) up to the NLO level and of the power corrections to the structure function F2. The fits of the combined data for the nonsinglet part of the structure function F2 predict the coupling constant value αs(MZ2) = 0.1174 ± 0.0007 (stat.) ± 0.0019 (syst.) ± 0.0010 (norm.) (or QCD parameter $$\Lambda \tfrac{{(5)}}{{MS}} = 204 \pm 25$$ (total experimental error) MeV). The fits of the combined data for both the nonsinglet part and the singlet part lead to the values αs(MZ2) = 0.1177 ± 0.0007 (stat.) ± 0.0021 (syst.) ± 0.0009 (norm.) (or QCD parameter $$\Lambda \tfrac{{(5)}}{{MS}}$$ =(208±27 (total experimental error)MeV). The above values are in very good agreement with each other. We estimate theoretical uncertainties for αs(MZ2) at +0.0047 and −0.0057 from fits of the combined data when complete singlet and nonsinglet Q2 evolution is taken into account.