Direct extraction of QCD Lambda(MS)over-bar from moments of structure functions in neutrino-nucleon scattering, using the CORGI approach

摘要

We use recently calculated next-to-next-to-leading (NNLO) anomalous dimension coefficients for the n = 1, 3, 5,..., 13 moments of the xF(3) structure function in nuN scattering, together with the corresponding three-loop Wilson coefficients, to obtain improved QCD predictions for the moments. The Complete Renormalization Group Improvement (CORGI) approach is used, in which all dependence on renormalization or factorization scales is avoided by a complete resummation of ultraviolet logarithms. The Bernstein Polynomial method is used to compare these QCD predictions to the xF(3) data of the CCFR Collaboration, and direct fits for Lambda(5)/MS, with N-f = 5 effective quark flavours, over the range 20 < Q(2) < 125.9 GeV2 were performed. We obtain Lambda(5)/MS = = 202(-45)(+54) MeV, corresponding to the three-loop running coupling alpha(S) (M-Z) = 0.1174(-0.0043)(+0.0043). Including target mass 0.0043' (5) corrections as well we obtain Lambda(5)/MS = 228(-36)(+35) MeV, corresponding to alpha(S) (M-Z) = 0. 1196(-0.0031)(+0.0027). (C) 2002 Elsevier Science B.V. All rights reserved. [References: 21]