Status of perturbative QCD calculations for deep-inelastic scattering and related processes

Abstract

We give a brief overview of the status of perturbative QCD calculations for deep-inelastic scattering. The radiative corrections to the Wilson coefficients are generally available to next-to-next-to-leading order in QCD and we address the accuracy of the strong coupling constant, the parton distributions of the nucleon and the heavy quark masses which is required for precision predictions. We also discuss related processes at hadron colliders such as Higgs production via weak boson fusion which can be described through structure functions of deep-inelastic scattering, building upon an approximate, although very accurate, factorization of the perturbative QCD corrections. Keywords: Deep-inelastic scatteringDeep-inelastic scattering (DIS) and the observed scaling violations have been central to the formulation of Quantum Chromodynamics (QCD) as the gauge theory of the strong interactions [1,2]. Over the decades the available high precision experimental data from lepton-and neutrino scattering off fixed targets at CERN, FNAL and SLAC as well as from electronproton collisions at the HERA collider at DESY have successfully probed QCD in a wide kinematical range. The key observables are inclusive structure functions or differential cross sections which provide the theoretical description of the hard hadronic interactions in the QCD improved parton model. Precision predictions in perturbative QCD rest on the fact that we can separate the sensitivity to dynamics from different scales, i.e., the physics at scale of the nucleon mass from hard highenergy scattering at a large scale Q 2 . In Fig. 1 this is depicted for lepton-proton DIS in the one-boson exchange approximation, see e.g., Ref. [3] for the definitions of the kinematic variables.The factorization at a scale µ allows to express for instance the unpolarized inclusive structure functions