Parton distributions for event generators

Abstract

In this paper, conventional global QCD analysis is generalized to produce parton distribution functions (PDFs) optimized for use with event generators at the Large Hadron Collider (LHC). This optimization is accomplished by complementing usual constraints on the PDFs from the existing hard-scattering experimental data with those needed to reproduce cross sections for key scattering processes at the LHC, as predicted by the best available theory, in the joint input to the global analysis. With the optimized PDFs, predictions obtained by event generators at a given order in the QCD coupling strength reproduce the representative LHC cross sections computed at one higher order. In the present study, the optimized PDFs for leading-order event generators were developed. Several optimization strategies and resulting candidate PDF sets (labeled as CT09MCS, CT09MC1 and CT09MC2) are compared with those from other approaches.