Electroweak higher-order effects and theoretical uncertainties in deep-inelastic neutrino scattering

A previous calculation of electroweak O(α) corrections to deep-inelastic neutrino scattering, as e.g. measured by NuTeV and NOMAD, is supplemented by higher-order effects. In detail, we take into account universal two-loop effects from Δα and Δρ as well as higher-order final-state photon radiation off muons in the structure function approach. Moreover, we make use of the recently released O(α)-improved parton distributions MRST2004QED and identify the relevant QED factorization scheme, which is DIS-like. As a technical by-product, we describe slicing and subtraction techniques for an efficient calculation of a new type of real corrections that are induced by the generated photon distribution. A numerical discussion of the higher-order effects suggests that the remaining theoretical uncertainty from unknown electroweak corrections is dominated by nonuniversal two-loop effects and is of the order 0.0003 when translated into a shift in sin²θW=1-MW²/MZ². The O(α) corrections implicitly included in the parton distributions lead to a shift of about 0.0004.