Collinear splitting, parton evolution and the strange-quark asymmetryof the nucleon

por German Rodrigo (IFIC)

martes 21 sept. 2004 15:00 → 16:00 Europe/Madrid

Sala Seminarios IFIC (Edf. Institutos de Investigación)

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 at present and future colliders. 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, and its relation to the NuTeV anomaly.