The DIS(chi) Scheme for Heavy Quark Production at Small x

Abstract

In order to successfully describe DIS data, one must take heavy quark mass effects into account. This is often achieved using so called variable flavour number schemes, in which a parton distribution for the heavy quark species is defined above a suitable matching scale. At small x, one must also potentially include high energy corrections to this framework arising from the BFKL equation. We outline the definition of a variable flavour scheme which allows such corrections to be consistently implemented alongside a fixed order QCD expansion. Results of a global fit using this scheme are presented. We also discuss an extension of the resummation to NLL order.