Collinear splitting, parton evolution and the strange-quark asymmetry of the nucleon in NNLO QCD

DANIEL DE FLORIAN; STEFANO CATANI; GERMAN RODRIGO; WERNER VOGELSANG

Zinnowitz

Congreso; 7th DESY Workshop on Elementary Particle Theory: Loops and Legs in Quantum Field Theory,; 2004

We consider the collinear limit of QCD amplitudes at one-loop order, and their factorization properties directly in colour space. These results apply to the multiple collinear limit of an arbitrary number of QCD partons, and are a basic ingredient in many higher-order computations. In particular, we discuss the triple collinear limit and its relation to flavour asymmetries in the QCD evolution of parton densities at three loops. As a phenomenological consequence of this new effect ,and of the fact that the nucleon has non-vanishing quark valence densities, we study the perturbative generation of a strange–antistrange asymmetry s(x) -\bar{s}(x) in the nucleon’s sea.