Quantum chromodynamics and deep inelastic scattering

We discuss the formalism involved in relating QCD calculations to experimental results in the deep inelastic region, and then present a high-order QCD calculation - the two-loop corrections to the Wilson coefficients of the moments of the longitudinal structure function (for the non-singlet case).We have calculated using massless quarks, and infra-red divergencesare regulated by keeping incoming and outgoing quarks slightly off mass-shell. We have analytic results for all but two of the diagrams calculated. Results are presented for three, four, five and six quark flavours, and for both the MS and MS renormalization schemes.