Steps towards NNLO QCD calculations: collinear factorization at O(\alpha_S^2)

Abstract

I consider the singular behaviour of tree-level QCD amplitudes when the momenta of three partons become simultaneously parallel and I discuss the universal factorization formula that controls the singularities of the multiparton matrix elements in this collinear limit.

Comments: 3 pages, 1 eps figure, talk given at the DIS99 Workshop, Zeuthen, Germany, April 19-23, 1999