A Leading–Order, But More Than One–Loop, Calculation of Structure Functions

I present a full leading–order calculation of F2(x,Q ) and FL(x,Q ), including contributions not only from leading order in αs, but also from the leading power of αs for each order in ln(1/x). The calculation is ordered according to the inputs and evolution of the structure functions, and the perturbative form of the inputs is determined. I compare the results of fits to data to those using conventional LO and NLO order calculations, and the correct inclusion of leading ln(1/x) terms is clearly preferred. A prediction for FL(x,Q ) is produced which is smaller at small x than that obtained from the conventional approach.