Hard processes in general factorisation scheme

Abstract

A framework for the formulation, in a general factorization scheme of QCD predictions for physical quantities involving parton distribution and/or fragmentation functions, is suggested. The main advantage of this method, based on the use of Jacobi polynomials and implying a novel parametrization of nonperturbative properties of hadrons, is that it allows an easy and straightforward transformation of the results of phenomenological analyses performed in arbitrary factorization scheme, into any other one. The study of nonsinglet nucleon structure functions furthermore demonstrates that the specification of the factorization convention, i.e. the way parton densities beyond the leading order are defined, may be as important as the choice of the factorization and hard scattering scalesM and μ.