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NNLO evolution of deep-inelastic structure functions: the non-singlet case

2000; Elsevier BV; Volume: 568; Issue: 1-2 Linguagem: Inglês

10.1016/s0550-3213(99)00668-9

1873-1562

W.L. van Neerven, A. Vogt,

High-Energy Particle Collisions Research

We study the next-to-next-to-leading order (NNLO) evolution of flavour non-singlet quark densities and structure functions in massless perturbative QCD. Present information on the corresponding three-loop splitting functions is used to derive parametrizations of these quantities, including Bjorken-x dependent estimates of their residual uncertainties. Compact expressions are also provided for the exactly known, but rather involved two-loop coefficient functions. The size of the NNLO corrections and their effect on the stability under variations of the renormalization scale are investigated. The residual uncertainty of the three-loop splitting functions does not lead to appreciable effects for x>10−2. Inclusion of the NNLO contributions reduces the main theoretical uncertainty of αs determinations from non-singlet scaling violations by more than a factor of two.