Leading ln(1/x) and Heavy Quark Corrections in Structure Functions

I present a calculation of structure functions at leading order which includes an unambiguous inclusion of the leading ln(1/x) terms for each power of alpha_s, and also the correct effects due to the mass of the charm and bottom quarks. I compare the results of fits to data to those obtained using conventional NLO in alpha_s calculations, noting a clear preference for my approach, especially at small x. The predictions for both the charm structure function and F_L(x,Q^2) using the two approaches are compared, the latter being much more discriminating.