Third-order QCD corrections to the charged-current structure function F3

We compute the coefficient function for the charge-averaged W-+/--exchange structure function F-3 in deep-inelastic scattering (DIS) to the third order in massless perturbative QCD. Our new three-loop contribution to this quantity forms, at not too small values of the Bjorken variable x, the dominant part of the next-to-next-to-next-to-leading order corrections. It thus facilitates improved determinations of the strong coupling alpha(s) and of 1/Q(2) power corrections from scaling violations measured in neutrino-nucleon DIS. The expansion of F-3 in powers of alpha(s) is stable at all values of x relevant to measurements at high scales Q(2). At small x the third-order coefficient function is dominated by diagrams with the colour structure d(abc)d(abc), not present at lower orders. At large x the coefficient function for F-3 is identical to that of F-1 up to terms vanishing for x -> 1. (C) 2009 Elsevier B.V. All rights reserved.