Theoretical uncertainties in the QCD evolution of structure functions and their impact on αs(MZ2)

Abstract The differences are discussed between various next-to-leading order prescriptions for the QCD evolution of parton densities and structure functions. Their quantitative impact is understood to an accuracy of 0.02%. The uncertainties due to the freedom to choose the renormalization and factorization scales are studied. The quantitative consequences of the different uncertainties on the extraction of the strong coupling constant α s from scaling violations in deep-inelastic scattering are estimated for the kinematic regime accessible at HERA.